JP2021014936A - Vapor chamber and method of manufacturing the same - Google Patents

Abstract

To provide a vapor chamber allowing a liquid-phase working fluid to flow easily.SOLUTION: A vapor chamber 1 includes a container C, a working fluid sealed in the container, and a wick body 30 sealed in the container and formed of a porous material. The wick body includes a plate-shaped base 31, and a plurality of protrusions 32 upwardly protruded from the base. The inner side of the protrusions and a portion positioned under the protrusions of the base are filled with the porous material.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vapor chamber and a method for manufacturing a vapor chamber.

Conventionally, as shown in Patent Document 1, a vapor chamber having a structure in which a working fluid and a porous wick body are sealed inside a container has been known. In Patent Document 1, the wick body has a hollow protrusion, and the space inside the protrusion is used as a vapor flow path for the working fluid.

Japanese Unexamined Patent Publication No. 2018-204841

If the protrusion is hollow as in Patent Document 1, when the working fluid of the liquid phase flows inside the wick body, it is necessary to bypass the hollow portion, so that the flow efficiency is lowered. ..

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a vapor chamber in which a working fluid in a liquid phase can easily flow.

In order to solve the above problems, the vapor chamber according to the first aspect of the present invention includes a container having a top plate and a bottom plate joined to each other, a working fluid sealed inside the container, and the container. A wick body enclosed inside and formed of a porous material is provided, and the wick body has a plate-shaped base portion and a plurality of convex portions protruding upward from the base portion. The inside of the plurality of convex portions and the portion of the base portion located below the plurality of convex portions are filled with the porous material.

According to the first aspect, the inside of the plurality of convex portions and the portion of the base portion located below the plurality of convex portions are filled with the porous material. Therefore, as compared with the case where the inside of the convex portion is hollow, for example, the working fluid of the liquid phase can be easily flowed inside the wick body.

Here, when the portion of the wick body in which the convex portion is located is defined as the region A1 and the portion in which the convex portion is not located in the plan view is defined as the region A2, the average porosity in the region A1 is defined. May be larger than the average porosity in the region A2, and the average pore diameter in the region A2 may be smaller than the average pore diameter in the region A1.

Further, the porous material may include a mesh material and a sintered powder material.

In the method for manufacturing a vapor chamber according to a second aspect of the present invention, a sheet material formed of a porous material is sandwiched between two rollers and compressed to form a plate-shaped base portion and the base portion. A wick body having a plurality of convex portions protruding upward is formed, and the wick body and the working fluid are sealed inside the container.

According to the second aspect, a wick body in which the inner part of the plurality of convex portions and the portion of the base portion located below the plurality of convex portions is filled with a porous material can be stably produced at low cost. can do.

According to the above aspect of the present invention, it is possible to provide a vapor chamber in which the working fluid of the liquid phase is easily flowed.

It is an exploded perspective view of the vapor chamber which concerns on this embodiment. It is sectional drawing of the vapor chamber which concerns on this embodiment in line II-II of FIG. It is a figure which shows the case where the wick body of FIG. 2 is manufactured by a mold. It is a figure which shows the case where the wick body of FIG. 2 is manufactured by two rollers. It is a figure which shows the case where the wick body of FIG. 2 is manufactured by two rollers and a plate.

Hereinafter, the vapor chamber of the present embodiment will be described with reference to the drawings.
As shown in FIG. 1, the vapor chamber 1 includes a container C and a wick body 30. Container C has a top plate 10 and a bottom plate 20 joined to each other. The container C is formed in a hollow rectangular parallelepiped shape. A wick body 30 and a working fluid (not shown) are enclosed inside the container C. The wick body 30 is formed of a porous material. The working fluid of the liquid phase impregnates the pores of the wick body 30 and flows in the wick body 30 due to the capillary force generated by the pores. The shape of the container C may be changed as appropriate as long as it is hollow.

The vapor chamber 1 is a heat transport element for transporting and diffusing heat by utilizing the latent heat of the working fluid to cool the heat source. The working fluid is a well-known heat transport medium capable of changing the phase, and undergoes a phase change between a liquid phase and a gas phase in the container C. For example, water (pure water), alcohol, ammonia, or the like can be adopted as the working fluid. The material of the container C is not particularly limited, but for example, copper can be preferably used.

The vapor chamber 1 is arranged at a position in contact with or adjacent to a heat source (for example, a CPU). The portion of the vapor chamber 1 near the heat source functions as an evaporation part of the working fluid, and the portion far from the heat source functions as a condensing part of the working fluid. In the evaporation section, the working fluid in the liquid phase evaporates by receiving heat from the heat source. The evaporated working fluid flows so as to diffuse from the evaporated portion through a gap (hereinafter referred to as a steam flow path) between the surface of the wick body 30 and the inner surface of the container C. The diffused working fluid of the gas phase is condensed by being deprived of heat by the outside air or the like via the container C in a portion (condensing portion) away from the heat source.

The condensed working fluid flows toward the evaporation part by the capillary force generated by the pores of the wick body 30. In the evaporation section, the working fluid in the liquid phase receives heat again and evaporates. By repeating such an action, the vapor chamber 1 can continuously transport and dissipate the heat of the heat source.

The thickness of the container C is not particularly limited, but is, for example, about 0.4 mm. By making the thickness of the container C in the vertical direction extremely small in this way, the vapor chamber 1 can be incorporated in an electronic device such as a mobile phone. When the vapor chamber 1 is built in an electronic device, for example, the heat generated by the CPU can be transported and dissipated to cool the CPU.

(Direction definition)
In the present embodiment, the direction in which the top plate 10 and the bottom plate 20 face each other is referred to as the vertical direction Z. In the vertical direction Z, the top plate 10 side is referred to as the upper side, and the bottom plate 20 side is referred to as the lower side. Viewing from the vertical direction Z is called plan view. Further, one direction orthogonal to the vertical direction Z is referred to as a front-rear direction X, and a direction orthogonal to both the vertical direction Z and the front-rear direction X is referred to as a horizontal direction Y.

The top plate 10 has an upper plate portion 11 and an upper side wall portion 12. The upper plate portion 11 extends in a plane orthogonal to the vertical direction Z. The upper plate portion 11 is formed in a rectangular shape that is longer in the left-right direction Y than in the front-rear direction X in a plan view. The upper side wall portion 12 extends downward from the outer peripheral edge of the upper plate portion 11.

The bottom plate 20 has a lower plate portion 21 and a lower side wall portion 22. The lower plate portion 21 extends in a plane orthogonal to the vertical direction Z. The lower plate portion 21 is formed in a rectangular shape that is longer in the left-right direction Y than in the front-rear direction X in a plan view. The lower side wall portion 22 extends upward from the outer peripheral edge of the lower plate portion 21.

The upper plate portion 11 and the lower plate portion 21 face each other with a gap in the vertical direction Z. As shown in FIG. 2, the upper side wall portion 12 and the lower side wall portion 22 face each other in the vertical direction Z, and are joined to each other by the joining material J. As the joining method, brazing, diffusion joining with silver, laser welding and the like can be used. When brazing is adopted, the bonding material J is a brazing material, and when diffusion bonding with silver is used, the bonding material J is silver. In addition, for example, when the top plate 10 and the bottom plate 20 are formed of the same material and both are diffusely bonded, the bonding material J is unnecessary. That is, the bonding material J may not be provided.

The shapes of the top plate 10 and the bottom plate 20 can be changed as appropriate. For example, the top plate 10 does not have to have the upper side wall portion 12. In this case, the lower side wall portion 22 may be joined to the outer peripheral edge of the upper plate portion 11. Alternatively, the bottom plate 20 may not have the lower side wall portion 22. In this case, the upper side wall portion 12 may be joined to the outer peripheral edge of the lower plate portion 21. Further, when the top plate 10 and the bottom plate 20 are joined by laser welding, a shape that facilitates laser welding may be adopted. For example, two flange portions protruding outward from the container C may be provided from the lower end edge of the upper side wall portion 12 and the upper end edge of the lower side wall portion 22, and the two flange portions may be joined to each other.

The wick body 30 has a plate-shaped base portion 31 and a plurality of convex portions 32 protruding upward from the base portion 31. The plurality of convex portions 32 are arranged at intervals in the front-rear direction X and the left-right direction Y. The plurality of convex portions 32 are formed in a substantially columnar shape, and the upper surface is circular. However, the shape of each convex portion 32 may be changed as appropriate.

As shown in FIG. 2, the upper surface of each convex portion 32 is in contact with the lower surface of the upper plate portion 11. Further, the lower surface of the base portion 31 is in contact with the joining material J provided on the upper surface of the lower plate portion 21. As a result, the wick body 30 also functions as a member that suppresses deformation of the container C in the vertical direction. That is, the wick body 30 has a role of improving the strength of the vapor chamber 1 in addition to the role of flowing the working fluid of the liquid phase.
The dimensions of the wick body 30 in the vertical direction are not particularly limited, but for example, the thickness of the base portion 31 is about 0.1 mm, and the amount of protrusion of the convex portion 32 upward is about 0.1 mm.

The lower surface of the base portion 31 is joined to the upper surface of the lower plate portion 21 by a joining material J. The side surface of the base portion 31 is joined to the inner surface of the lower side wall portion 22 by a joining material J. The method of joining the wick body 30 and the bottom plate 20 may be the same as or different from the method of joining the top plate 10 and the bottom plate 20. Further, the wick body 30 may not be joined to the bottom plate 20, but the wick body 30 may be simply sandwiched between the top plate 10 and the bottom plate 20. In this case, the bonding material J may not be provided between the wick body 30 and the bottom plate 20.

In the example of FIG. 2, the layer of the bonding material J is between the upper side wall portion 12 and the lower side wall portion 22, between the base portion 31 and the lower side wall portion 22, and between the base portion 31 and the lower plate portion 21. Is continuously provided. According to such a configuration, for example, the top plate 10 and the bottom plate 20 can be joined, and the bottom plate 20 and the wick body 30 can be joined at the same time.

In the present embodiment, the inside of the plurality of convex portions 32 and the portion of the base portion 31 located below the plurality of convex portions are filled with the porous material forming the wick body 30. Further, the lower surface of the base portion 31 has a flat shape except that it has a fine uneven shape of the porous material.

The wick body 30 is formed of a porous material and has a large number of pores that exert a capillary force on the working fluid of the liquid phase. As the porous material, for example, a mesh material in which a plurality of fine wires are woven in a grid pattern can be used. As the thin wire forming the mesh, for example, a copper material having a high thermal conductivity can be preferably used.

The material of the wick body 30 can be changed as appropriate. For example, the wick body 30 may be formed by sintering a powder material containing a metal. Further, a porous material other than the mesh material or the powder material may be adopted.
Here, the mesh material has higher strength than the sintered powder material, but has a large pore diameter. On the contrary, the sintered powder material can have a smaller pore diameter than the mesh material, but has low strength and is easily cracked by, for example, impact.

Therefore, the wick body 30 may be formed by using both the mesh material and the sintered powder material. Specifically, after forming the base portion 31 and the plurality of convex portions 32 with the mesh material, the powder material may be attached to the surface of the mesh material and the powder material may be sintered. Alternatively, the powder material may be attached to the surface of the sheet-shaped mesh material, the powder material may be sintered, and then the base portion 31 and the plurality of convex portions 32 may be formed.

Next, an example of a method for manufacturing the vapor chamber 1 will be described.

The top plate 10 and the bottom plate 20 can be formed by cutting or die processing.
As a method for forming the wick body 30, for example, a mold 100 as shown in FIG. 3 may be used. The mold 100 has a lower mold portion 101 and an upper mold portion 102. The upper surface of the lower mold portion 101 is a flat surface. On the lower surface of the upper mold portion 102, a concave-convex shape for forming a plurality of convex portions 32 of the wick body 30 is formed. The wick body 30 can be formed by sandwiching the sheet material S formed of the porous material between the lower mold portion 101 and the upper mold portion 102 and compressing the sheet material S.

Further, as a method for forming the wick body 30, two rollers 201 and 202 as shown in FIGS. 4 and 5 may be used.
In the example of FIG. 4, a plurality of holes 202a are formed in the upper roller 202. The position, number, size, and depth of the holes 202a correspond to the plurality of protrusions 32 of the wick body 30. The distance between the two rollers 201 and 202 is smaller than the thickness of the sheet material S forming the wick body 30. Therefore, by passing the sheet material S between the two rollers 201 and 202, the portion where the hole 202a is not formed is compressed. On the other hand, in the portion where the hole 202a is formed, the sheet material S is not compressed, or is compressed at a lower compression rate than the portion where the hole 202a is not formed. As a result, the wick body 30 having the base portion 31 and the plurality of convex portions 32 is formed. If necessary, the base portion 31 may be cut to adjust the outer shape of the wick body 30.

In the example of FIG. 5, a plate 203 is used in addition to the two rollers 201 and 202. The plate 203 is made of a hard material such as metal. A plurality of holes 203a are formed in the plate 203. The position, number, and size of the holes 203a and the thickness of the plate 203 correspond to the positions and shapes of the plurality of convex portions 32 of the wick body 30.

In FIG. 5, the distance between the two rollers 201 and 202 is smaller than the total thickness of the sheet material S and the plate 203 forming the wick body 30. Therefore, by passing the sheet material S and the plate 203 in an overlapping manner between the two rollers 201 and 202, the portion where the hole 203a is not formed is compressed. On the other hand, in the portion where the hole 203a is formed, the sheet material S is not compressed, or is compressed at a lower compression rate than the portion where the hole 203a is not formed. As a result, the wick body 30 having the base portion 31 and the plurality of convex portions 32 is formed. In the example of FIG. 5, it is not necessary to form a hole in the upper roller 202.

A container C is formed by accommodating the wick body 30 between the top plate 10 and the bottom plate 20 and joining the top plate 10 and the bottom plate 20. When joining the top plate 10 and the bottom plate 20, the wick body 30 and the bottom plate 20 may be joined at the same time.
After that, the vapor chamber 1 is manufactured by filling the container C with a working fluid from a filling hole (not shown) formed in advance and closing the filling hole.

Here, regardless of which method of FIGS. 3 to 5 is used to form the wick body 30, the portion of the wick body 30 in which the convex portion 32 is not provided is compressed more strongly than the portion in which the convex portion 32 is provided. Will be done. Therefore, the average porosity and the size of the pores are different between the region A1 and the region A2 shown in FIG. The region A1 is a portion of the wick body 30 provided with the convex portion 32 in a plan view. The region A2 is a portion of the wick body 30 in which the convex portion 32 is not provided in a plan view.

In the region A2, the wick body 30 is strongly compressed, so that the average porosity and the average pore diameter are smaller than those in the region A1. On the contrary, in the region A1, the wick body 30 is not compressed or the degree of compression is weaker than that of the region A2, so that the average porosity and the average pore diameter are larger than those of the region A2. The average porosity in region A1 is, for example, 67.7%, and the average porosity in region A2 is, for example, 35.4%.

In the portion where the average porosity is large, the holding capacity of the working fluid in the liquid phase is high and the flow resistance is small. Further, in the portion where the average pore diameter is small, the capillary force acting on the working fluid of the liquid phase is large. Therefore, since the region A1 has a large average porosity, the holding capacity of the working fluid in the liquid phase is high, and the flow resistance is small. On the other hand, since the region A2 has a small average pore diameter, the capillary force acting on the working fluid of the liquid phase is large. In the cross section shown in FIG. 2, such regions A1 and A2 are alternately repeated in the left-right direction Y.

As described above, the vapor chamber 1 of the present embodiment includes a wick body 30 formed of a porous material, and the wick body 30 has a plate-shaped base portion 31 and faces upward from the base portion 31. It has a plurality of protruding portions 32 and protrusions 32. The inside of the plurality of convex portions 32 and the portion of the base portion 31 located below the plurality of convex portions 32 are filled with the porous material. According to this configuration, as compared with the case where the inside of the convex portion 32 is hollow, for example, the working fluid of the liquid phase can easily flow inside the wick body 30 while improving the strength of the wick body 30 in the vertical direction. can do.

Further, when the portion of the wick body 30 in which the convex portion 32 is located is defined as the region A1 and the portion in which the convex portion 32 is not located in the plan view is defined as the region A2, the average porosity in the region A1 is in the region A2. It is larger than the average porosity, and the average pore diameter in the region A2 is smaller than the average pore diameter in the region A1. With this configuration, the working fluid of the liquid phase can be efficiently held in the region A1 having a large average porosity, and the working fluid of the liquid phase can be quickly supplied toward the evaporation part of the working fluid.

Further, by applying a large capillary force to the working fluid of the liquid phase in the region A2 having a small average pore diameter, the working fluid can be more reliably flowed from the condensing part to the evaporating part. In particular, when the vapor chamber 1 is built in a mobile phone or the like, it may be necessary to flow the working fluid of the liquid phase against gravity. Even in such a case, the large capillary force generated in the region A2 allows the working fluid of the liquid phase to flow against gravity.

Further, the porous material forming the wick body 30 may include a mesh material and a sintered powder material. In this case, the pore diameter of the pores of the wick body 30 can be reduced by the sintered powder body while ensuring the strength of the wick body 30 by the mesh material.

Further, as a method for manufacturing the vapor chamber 1, the sheet material S is sandwiched between two rollers 201 and 202 and compressed to form a plate-shaped base portion 31 and a plurality of plates protruding upward from the base portion 31. The wick body 30 having the convex portion 32 and the wick body 30 may be formed, and the wick body 30 and the working fluid may be sealed inside the container C. According to this manufacturing method, the wick body 30 in which the inner part of the plurality of convex portions 32 and the portion of the base portion 31 located below the plurality of convex portions 32 is filled with the porous material is stable at low cost. Can be manufactured.

Further, according to the above-mentioned production method, the wick body has a characteristic that the average porosity in the region A1 is larger than the average porosity in the region A2 and the average pore diameter in the region A2 is smaller than the average porosity in the region A1. 30 can be manufactured stably at low cost.

The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

For example, in the above embodiment, one wick body 30 is enclosed inside the container C. However, for example, a plurality of wick bodies 30 may be arranged side by side in the front-rear direction X or the left-right direction Y. Alternatively, a plurality of wick bodies 30 may be arranged so as to be stacked in the vertical direction Z.

Further, the method for manufacturing the vapor chamber 1 described in the above embodiment is an example, and can be appropriately changed.

In addition, it is possible to replace the constituent elements in the above-described embodiment with well-known constituent elements as appropriate without departing from the spirit of the present invention, and the above-described embodiments and modifications may be appropriately combined.

1 ... Vapor chamber 10 ... Top plate 20 ... Bottom plate 30 ... Wick body 31 ... Base part 32 ... Convex parts 201, 202 ... Rollers

Claims (4)

With a container with top and bottom plates joined to each other,
The working fluid enclosed inside the container and
A wick body, which is sealed inside the container and formed of a porous material, is provided.
The wick body has a plate-shaped base portion and a plurality of convex portions protruding upward from the base portion.
A vapor chamber in which the inside of the plurality of convex portions and the portion of the base portion located below the plurality of convex portions are filled with the porous material. When the portion of the wick body in which the convex portion is located is defined as the region A1 and the portion in which the convex portion is not located in the plan view is defined as the region A2.
The average porosity in the region A1 is larger than the average porosity in the region A2.
The vapor chamber according to claim 1, wherein the average pore diameter in the region A2 is smaller than the average pore diameter in the region A1. The vapor chamber according to claim 1 or 2, wherein the porous material contains a mesh material and a sintered powder material. A wick body having a plate-shaped base portion and a plurality of convex portions protruding upward from the base portion by sandwiching and compressing a sheet material formed of a porous material between two rollers. Form and
A method for manufacturing a vapor chamber in which the wick body and the working fluid are sealed inside a container.

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