JP2022013309A - Heat conduction member and manufacturing method of the same - Google Patents

Abstract

To provide a heat conduction member which enables improvement of productivity, and to provide a manufacturing method of the heat conduction member.SOLUTION: A heat conduction member includes: a housing which houses a working medium and has a space therein; and at least one support pillar located in the housing. The housing has a first plate 4 and a second plate which are disposed facing each other. At least one of the first plate and the second plate has a recessed part 4a. The support pillars 7 are located in the recessed part. The support pillar has: a body part 7a which contacts with the first plate; and a head 7B which is located at the opposite side of the first plate with respect to the body part. The head has: a plane part 7f facing the second plate; and a curved surface 7R connected to the plane part.SELECTED DRAWING: Figure 4

Description

The present invention relates to a heat conductive member and a method for manufacturing the same.

Conventionally, a vapor chamber as a heat conductive member has been proposed. The vapor chamber has a housing that seals a working medium such as water. The housing has, for example, a base having a recess and a flat plate-shaped lid. The lid is placed over the base to seal the recess. A support portion is arranged in the recess. As a result, the lid portion is supported by the support portion, and the housing is less likely to be crushed. The support portion is formed, for example, by sintering copper powder (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-194515

When copper powder is applied to the recesses in order to form a support portion in the recesses of the base, the surface shape of the copper powder becomes a convex shape toward the lid portion. When the copper powder is sintered to form the support portion in this state, the head portion of the support portion, that is, the end portion of the support portion opposite to the bottom surface of the recess, has a curved surface shape that is convex toward the lid portion. Is formed.

At this time, if the height of the support portion is larger than the depth of the recess, that is, if the apex of the head of the support portion protrudes from the recess to the lid portion side, the support portion becomes an obstacle and the lid portion is attached to the base. Will be difficult to contact. Therefore, it is difficult to join the lid portion to the base to seal the concave portion. Therefore, in order to securely seal the concave portion with the lid portion, it is necessary to control the height of the support portion with high accuracy so that the height of the support portion matches the depth of the concave portion. However, controlling the height of the support portion with high accuracy may reduce the productivity of the vapor chamber.

In view of the above points, it is an object of the present invention to provide a heat conductive member capable of improving productivity and a method for manufacturing the same.

An exemplary heat-conducting member of the present invention is a heat-conducting member that accommodates a working medium and includes a housing having a space inside, and at least one support column located in the housing. Has a first plate and a second plate arranged to face each other, at least one of the first plate and the second plate has a recess, and the strut is located in the recess and said. The strut has a main body portion that comes into contact with the first plate and a head portion that is located on the opposite side of the main body portion from the first plate portion, and the head portion faces the second plate. It has a flat surface portion and a curved surface portion connected to the flat surface portion.

An exemplary method for manufacturing a heat conductive member of the present invention uses a first plate and a second plate having at least one recessed portion, a support column forming step of forming a support column on the first plate, and a main body portion of the support column. A flat surface portion forming step of forming a flat surface portion by processing a part of the curved surface portion of the head located on the opposite side of the first plate, and the second plate facing the flat surface portion. It comprises a joining step of arranging and joining the second plate and the first plate to position the column in the recess.

According to the present invention, the productivity of the heat conductive member can be improved.

FIG. 1 is a cross-sectional view showing a schematic configuration of a vapor chamber as a heat conductive member according to an embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing the structure of a support column provided in the vapor chamber. FIG. 3 is a cross-sectional view schematically showing a metal paste used for forming a support column. FIG. 4 is an enlarged cross-sectional view showing the columns. FIG. 5 is a flowchart showing the flow of the manufacturing process of the vapor chamber. FIG. 6 is a cross-sectional view showing a part of the manufacturing process of the vapor chamber. FIG. 7 is a cross-sectional view showing a part of the manufacturing process of the vapor chamber. FIG. 8 is an enlarged cross-sectional view showing a support column formed on the first plate in the primary step. FIG. 9 is a cross-sectional view showing another manufacturing process of the vapor chamber. FIG. 10 is a cross-sectional view schematically showing another configuration of the vapor chamber. FIG. 11 is a cross-sectional view schematically showing still another configuration of the vapor chamber. FIG. 12 is a cross-sectional view schematically showing still another configuration of the vapor chamber.

Hereinafter, the vapor chamber 1 as a heat conductive member according to an exemplary embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the XYZ coordinate system is shown as a three-dimensional Cartesian coordinate system as appropriate. In the XYZ coordinate system, the Z-axis direction indicates a vertical direction (that is, a vertical direction), the + Z direction is the upper side (opposite the gravity direction), and the −Z direction is the lower side (gravity direction). The Z-axis direction is also the opposite direction between the first plate 4 and the second plate 5, which will be described later. The X-axis direction refers to a direction orthogonal to the Z-axis direction, and one direction and the opposite direction thereof are the + X direction and the −X direction, respectively. The Y-axis direction refers to a direction orthogonal to both the Z-axis direction and the X-axis direction, and one direction and the opposite direction thereof are the + Y direction and the −Y direction, respectively.

As used herein, the "particle size" of a particle refers to the maximum outer diameter of the particle. For example, when the particles are spherical, the diameter of the particles, which is the maximum outer diameter of the particles, is the "particle size". On the other hand, when the particles have a shape other than a sphere, the outer diameter of the particles differs depending on the direction. In this case, the largest outer diameter obtained in each direction is the "particle size" of the particles.

As used herein, the term "sintering" refers to a technique of heating a metal powder or a paste containing the metal to a temperature lower than the melting point of the metal to bake the metal particles. The "sintered body" refers to an object obtained by sintering.

(1. Configuration of vapor chamber)
FIG. 1 is a cross-sectional view showing a schematic configuration of a vapor chamber 1 according to an embodiment of the present invention. The vapor chamber 1 is a heat conductive member that transports the heat of the heating element H. As the heating element H, for example, an electronic component that generates heat or a substrate on which the electronic component is mounted can be considered. The heating element H is cooled by the transport of heat by the vapor chamber 1. Such a vapor chamber 1 is mounted on an electronic device having a heating element H, such as a smartphone or a notebook personal computer.

The vapor chamber 1 includes a heated portion 101 and a heat radiating portion 102. The heated portion 101 is arranged in contact with the heating element H, for example, and is heated by the heat generated by the heating element H. The heat radiating unit 102 releases the heat of the working medium 2, which will be described later, heated by the heated unit 101 to the outside.

The vapor chamber 1 includes a housing 1a. A part of the housing 1a is included in the heated portion 101. The other part of the housing 1a is included in the heat radiating unit 102.

The housing 1a has a space 1b inside. The space 1b is a closed space, and is maintained in a reduced pressure state where the atmospheric pressure is lower than the atmospheric pressure, for example. When the space 1b is in a reduced pressure state, the working medium 2 housed in the space 1b is likely to evaporate. The thickness of the housing 1a in the Z-axis direction is, for example, 100 μm or more and 1000 μm or less.

The working medium 2 is housed in the space 1b inside the housing 1a. The working medium 2 is used to transport heat. The working medium 2 is, for example, water, but may be another liquid such as alcohol. That is, the vapor chamber 1 of the present embodiment includes a housing 1a that houses the working medium 2 and has a space 1b inside.

The housing 1a has a first plate 4. The first plate 4 is a metal plate that supports the support column 7 described later from the −Z direction side. That is, the housing 1a has a first plate 4 that supports the support column 7. In this embodiment, the metal constituting the first plate 4 is copper. The first plate 4 may be formed by plating the surface of a metal other than copper with copper. As the metal other than copper, for example, stainless steel can be considered. The first plate 4 is formed in a concave shape recessed in the −Z direction. That is, the first plate 4 has a recess 4a recessed in the −Z direction.

The housing 1a further has a second plate 5. The second plate 5 is located facing the first plate 4 in the Z-axis direction. More specifically, the second plate 5 is located on the + Z direction side with respect to the first plate 4, and covers the column 7 on the first plate 4 from the + Z direction side. That is, the housing 1a has a first plate 4 and a second plate 5 arranged so as to face each other. The second plate 5 is formed of, for example, a flat plate.

The second plate 5 is made of the same metal material as the first plate 4. Therefore, when the first plate 4 is made of copper, the second plate 5 is also made of copper. When the first plate 4 is made of a metal plate having a surface of stainless steel plated with copper, the second plate 5 is also made of a metal plate having a surface of stainless steel plated with copper.

In this embodiment, at least one of the first plate 4 and the second plate 5 has a recess. The support column 7 is located in the recess. The configuration in which only the second plate 5 has a recess and the configuration in which both the first plate 4 and the second plate have a recess will be described later (see FIGS. 10 and 11).

The housing 1a further has a joint 6. The joint portion 6 has a joint structure in which the first plate 4 and the second plate 5 are connected at their respective outer edges. In the housing 1a, the joint portion 6 is a combination of one or more columns 7 from both sides in the X direction (+ X direction side, −X direction side) and both sides in the Y direction (+ Y direction side, −Y direction side). It is in a pinching position. That is, the housing 1a has a joint portion 6 that connects the first plate 4 and the second plate 5. The joint portion 6 is located so as to sandwich the support column 7 in a direction perpendicular to the facing direction between the first plate 4 and the second plate 5.

The method of joining the first plate 4 and the second plate 5 is not particularly limited. For example, any bonding method such as hot pressing, diffusion bonding, or bonding using a brazing material may be used.

Both hot pressing and diffusion joining are methods of joining two members by heating and pressurizing, but they are distinguished from each other in the following points. In diffusion bonding, for example, by heating and pressurizing for several hours, atoms or particles near the bonding interface of the two members are diffused to bond the two members.

On the other hand, in the hot press, only some atoms or particles near the bonding interface of the two members are diffused by heating and pressurizing at a lower temperature and in a shorter time than the diffusion bonding, and the two members are bonded. do.

In diffusion bonding, the bonding interface itself disappears due to the difference in the degree of diffusion of atoms or particles. On the other hand, in hot pressing, a part of the bonding interface disappears and the rest is maintained as it is. Therefore, the bonding portion 6 formed by diffusion bonding and the bonding portion 6 formed by hot pressing have different bonding structures near the bonding interface. Also, due to the difference in heating and pressurizing times, the hot press has a shorter manufacturing tact time than the diffusion bonding.

The joint portion 6 may include a sealing portion. The sealing portion is, for example, a portion where an injection port for injecting the working medium 2 into the housing 1a is sealed by welding in the manufacturing process of the vapor chamber 1.

In the housing 1a, at least one support column 7 is located in the space 1b accommodating the working medium 2. That is, the vapor chamber 1 of the present embodiment includes at least one support column 7 located in the housing 1a. The column 7 is a columnar support or support extending in the Z direction. The cross section of the support column 7 on the XY surface is, for example, circular, but may have other shapes such as an elliptical shape.

The stanchion 7 is located on the first plate 4 and is supported by the first plate 4. That is, in the support column 7, the end portion on the −Z direction side comes into contact with the first plate 4. On the other hand, in the support column 7, the end portion on the + Z direction side comes into contact with the second plate 5. Therefore, the height of the column 7 in the Z direction coincides with the depth of the recess 4a of the first plate 4 in the Z direction. By locating the support column 7 in the housing 1a, a space 1b for accommodating the working medium 2 is secured in the housing 1a, and the housing 1a is prevented from being crushed by an external force.

The columns 7 whose height in the Z direction coincides with the depth of the recess 4a of the first plate 4 in the Z direction do not have to be all columns 7.

The strut 7 is made of, for example, a porous copper sintered body, and has a wick structure for internally transporting the working medium 2 by a capillary phenomenon. That is, the support column 7 has a porous wick structure. The details of the structure of the support column 7 will be described later.

In this embodiment, the plurality of columns 7 are located on the first plate 4 apart from each other in the X direction and the Y direction. That is, the columns 7 are scattered in the housing 1a.

In the vapor chamber 1 having the above configuration, the heated portion 101 is heated by the heat generated by the heating element H. When the temperature of the heated portion 101 rises, the working medium 2 housed in the space 1b inside the housing 1a is vaporized. The vaporized steam moves inside the vapor chamber 1 toward the heat dissipation unit 102. In the heat radiating unit 102, the steam is cooled and liquefied by the heat radiating. The liquefied working medium 2 flows along the inner surface of the housing 1a or inside the support column 7 due to a capillary phenomenon, and moves toward the heated portion 101. In FIG. 1, the flow of vapor vaporized by the working medium 2 is indicated by a black arrow, and the flow of the liquid working medium 2 is indicated by a white arrow. As the working medium 2 moves while changing its state as described above, heat is continuously transported from the heated portion 101 side to the heat radiating portion 102 side.

(2. Strut structure)
Next, the structure of the support column 7 will be described. FIG. 2 is a cross-sectional view schematically showing the structure of the support column 7. Further, FIG. 3 is a cross-sectional view schematically showing the metal paste 70 used for forming the support column 7. The cross sections of FIGS. 2 and 3 are arbitrary cross sections, that is, cross sections at arbitrary positions in the Y-axis direction.

The support column 7 includes a plurality of micro copper particles 71 and a copper body 72. The micro copper particles 71 are metal particles in which a plurality of copper atoms are aggregated or bonded. That is, the support column 7 contains a plurality of metal particles. The particle size of the micro copper particles 71 is 1 μm or more and less than 1 mm. The micro copper particles 71 are, for example, porous and have pores 71p that are voids inside. In FIG. 2, for the purpose of clearly distinguishing the micro copper particles 71 and the copper body 72, the micro copper particles 71 are shown without hatching for convenience.

The copper body 72 is a copper molten body in which the sub-micro copper particles 72a shown in FIG. 3 are melted and solidified by sintering. The sub-micro copper particles 72a are particles in which a plurality of copper atoms are aggregated or bonded. The particle size of the sub-micro copper particles 72a before melting is 0.1 μm or more and less than 1 μm. The copper body 72 is located around the plurality of micro copper particles 71.

The copper body 72 includes a first copper particle connecting portion 721 and a second copper particle connecting portion 722. The first copper particle connecting portion 721 connects adjacent micro copper particles 71 to each other at a distance of less than 1 μm. Such a first copper particle connecting portion 721 is formed by sintering sub-micro copper particles 72a located between adjacent micro copper particles 71 and in contact with them.

That is, the particle size of the sub-micro copper particles 72a before melting is less than 1 μm as described above. Therefore, when the sub-micro copper particles 72a located between the adjacent micro-copper particles 71 are melted and baked, the connecting distance between the adjacent micro-copper particles 71 by the first copper particle connecting portion 721 becomes less than 1 μm.

That is, the support column 7 includes a plurality of micro copper particles 71 having a particle size of 1 μm or more as a plurality of metal particles, and a copper body 72 located around the plurality of micro copper particles 71. The copper body 72 includes a first copper particle connecting portion 721 that connects adjacent micro copper particles 71 to each other at a distance of less than 1 μm. In the support column 7, the micro copper particles 71 are connected in a mesh pattern via the first copper particle connecting portion 721.

The second copper particle connecting portion 722 connects a part of the plurality of micro copper particles 71 and the first plate 4 at a distance of less than 1 μm. As a part of the plurality of micro copper particles 71, for example, among the plurality of micro copper particles 71, the micro copper particles 71 located at a position facing the first plate 4 at a distance of less than 1 μm can be considered.

Such a second copper particle connecting portion 722 is formed by sintering sub-micro copper particles 72a located between the micro copper particles 71 and the first plate 4. That is, the particle size of the submicro copper particles 72a is less than 1 μm as described above. Therefore, when the sub-micro copper particles 72a located between the micro-copper particles 71 and the first plate 4 are melted and baked, the micro-copper particles 71 and the first plate 4 are formed by the second copper particle connecting portion 722. The connection distance is less than 1 μm.

That is, the copper body 72 further includes a second copper particle connecting portion 722 in addition to the first copper particle connecting portion 721. The second copper particle connecting portion 722 connects a part of the plurality of micro copper particles 71 and the first plate 4 at a distance of less than 1 μm.

The strut 7 further includes a gap SP. The gap SP is a space that forms a flow path of the working medium 2 together with the hole 71p of the micro copper particles 71 described above. In the support column 7, in addition to the micro copper particles 71 and the copper body 72 described above, the presence of the hole portion 71p and the void portion SP constitutes the porous support column 7. The height of the support column 7 in the Z-axis direction is 50 μm or more and 200 μm or less. Therefore, the support column 7 is thin and has a relatively low height.

Here, the ratio of the volume of the space to the total volume of the columns 7 is called the porosity. The unit of porosity is%. The space includes the hole 71p and the void SP. The porosity is determined by the following method. For example, the porosity can be obtained by measuring the area of the space from the cross-sectional photograph of the support column 7 and calculating the ratio of the area of the space to the whole. When observing the cross section of the support column 7, it is preferable to use a scanning electron microscope having a deep depth of field. The method of observing the cross section is not particularly limited as long as it can easily distinguish between the metal portion and the space. Also. It is preferable that the observation range of the cross section is a viewing range that covers the entire cross section at least in the height direction of the support column 7 and can discriminate between the metal portion and the space. Specifically, the observation range of the cross section is an angle range that covers the maximum diameter of the cross section of 200 μm or more and 1000 μm or less. Further, for the calculation of the void ratio based on the observation photograph, it is preferable to use image analysis software capable of dividing the metal part and the space by binarizing the grayscale image and calculating the area of each part.

The porosity can also be obtained by the following calculation. That is, the total product of the columns 7 is V0 cm ³ . The volume of copper contained in the support column 7 is V1 cm ³ . The volume of the space included in the support column 7 is V2 cm ³ . In this case, V0 = V1 + V2. Further, where P is the porosity, P = V2 / V0 = (V0-V1) / V0 = 1- (V1 / V0). Here, V1 = (mass of copper) / (density of copper) = (mass of column) / (density of copper). The density of copper is known and is 8.96 g / cm ³ . The unit of mass is g. The mass and total product V0 of the columns 7 can be determined by measurement or calculation. Therefore, the porosity P of the support column 7 can be obtained from P = 1- (V1 / V0).

(3. Details of metal paste)
Next, the details of the metal paste 70 used for forming the support column 7 will be described. As shown in FIG. 3, the metal paste 70 further contains a resin 73 in addition to the above-mentioned micro copper particles 71 and sub-micro copper particles 72a.

The resin 73 is a volatile resin that volatilizes at a temperature equal to or lower than the melting point of copper constituting the micro copper particles 71 and the copper body 72. As such a volatile resin, for example, a cellulose resin such as methyl cellulose or ethyl cellulose, an acrylic resin, a butyral resin, an alkyd resin, an epoxy resin, a phenol resin or the like can be used. Among these, it is preferable to use an acrylic resin having high thermal decomposability.

The metal paste 70 further contains a dispersion medium that dissolves the resin 73. Examples of the dispersion medium include hydrocarbon solvents, cyclic ether solvents, ketone solvents, alcohol compounds, polyhydric alcohol ester solvents, polyhydric alcohol ether solvents, terpene solvents, and mixtures thereof. Etc. can be used. Among these, for example, texanol and terpineol having a boiling point near 200 ° C. can be preferably used.

The particle size of the micro copper particles 71 and the sub-micro copper particles 72a, the compounding ratio or the weight ratio of each component contained in the metal paste 70, and the like may be appropriately set so as to obtain a desired porosity of the support column 7. ..

(4. About the shape of the support)
FIG. 4 is an enlarged cross-sectional view showing the support column 7. The support column 7 has a main body portion 7A and a head portion 7B. The main body 7A is located in contact with the first plate 4. The head portion 7B is located on the side opposite to the first plate 4 with respect to the main body portion 7A and is connected to the main body portion 7A. That is, the support column 7 has a main body portion 7A that comes into contact with the first plate 4, and a head portion 7B that is located on the opposite side of the main body portion 7A from the first plate 4.

Here, as will be described later, the support column 7 is formed by applying the metal paste 70 onto the first plate 4 and firing it. When the viscous metal paste 70 is applied onto the first plate 4, the end portion on the −Z direction side corresponding to the “hem” of the metal paste 70 spreads in the X direction and the Y direction. Therefore, when the metal paste 70 is fired to form the support column 7, the support column 7 becomes thinner from the −Z direction toward the + Z direction, and the end portion on the + Z direction side protrudes toward the second plate 5. It has a shape (see FIG. 8). In the present embodiment, the end portion of the support column 7 having the curved surface shape on the + Z direction side is processed to flatten the end portion.

Specifically, as shown in FIG. 4, the head portion 7B of the support column 7 has a flat surface portion 7F and a curved surface portion 7R. The flat surface portion 7F is formed by processing a part of the curved surface portion 7R. As a result, the flat surface portion 7F faces the second plate 5 shown in FIG. As a method of processing a part of the curved surface portion 7R, there are methods such as cutting, pressing, and polishing. The curved surface portion 7R is connected to the flat surface portion 7R and is connected to the main body portion 7A. That is, the head portion 7B has a flat surface portion 7F facing the second plate 5 and a curved surface portion 7R connected to the flat surface portion 7F.

Here, assuming that the depth of the recess 4a of the first plate 4 is D (μm) and the height of the columns 7 is Ht (μm), in this embodiment, Ht = D for all the columns 7. There is. As described above, some of the columns 7 may have Ht <D.

(5. Manufacturing method of vapor chamber)
Next, a method for manufacturing the vapor chamber 1 of the present embodiment will be described. FIG. 5 is a flowchart showing the flow of the manufacturing process of the vapor chamber 1. 6 and 7 are cross-sectional views showing a manufacturing process of the vapor chamber 1. In FIG. 5, S indicates a start and E indicates an end. Further, in FIG. 6, for convenience, the joint position between the first plate 4 and the second plate 5, that is, the position of the end portion of the recess 4a on the + Z direction side is indicated by the broken line T. The method for manufacturing the vapor chamber 1 includes a support column forming step S1, a flat surface portion forming step S2, and a joining step S3.

(5-1. Strut forming process)
In the support column forming step S1, the first plate 4 having the recess 4a is used to form the support column 7 in the recess 4a. In the support column forming step S1, the support column 7 may be formed on the flat plate-shaped first plate 4 by using the flat plate-shaped first plate 4 and the second plate 5 having a recess. Further, the support 7 may be formed in the recess 4a of the first plate 4 by using the first plate 4 having the recess 4a and the second plate 5 having the recess. That is, the method for manufacturing the vapor chamber 1 includes a support column forming step S1 in which a support column 7 is formed on the first plate 4 by using a first plate 4 and a second plate 5 having at least one recess.

Specifically, the metal paste 70 is applied to the inside of the recess 4a of the first plate 4 with a thickness of 50 μm or more and 200 μm or less. The metal paste 70 contains metal particles, a resin 73, and a dispersion medium. Since the metal paste 70 has viscosity, when the metal paste 70 is applied to the recess 4a of the first plate 4, the metal paste 70 has a shape in which the cross-sectional area in the XY cross section becomes narrower in the + Z direction. In this state, the first plate 4 is placed in a heating furnace together with the metal paste 70 and heated. The heating temperature at this time is, for example, 400 ° C., and the heating time is, for example, 1 hour.

By heating the metal paste 70, the resin 73 contained in the metal paste 70 is volatilized, and the submicro copper particles 72a are melted by sintering and baked. As a result, the support column 7 including the first copper particle connecting portion 721 and the second copper particle connecting portion 722 is formed. Further, by appropriately setting the mixing ratio of the metal particles and the like, the support column 7 including the porous wick structure having a predetermined porosity is formed. Since the micro copper particles 71 have a larger particle size than the sub-micro copper particles 72a, they melt more slowly than the sub-micro copper particles 72a. Therefore, the micro copper particles 71 remain in the form of particles. The strut forming step S1 for forming the strut 7 by firing the metal paste 70 is also referred to as a “primary step”.

FIG. 8 is an enlarged cross-sectional view showing the support column 7 formed on the first plate 4 in the primary step. When the metal paste 70 having the above shape is fired to form the support column 7, the support column 7 is formed in a shape in which the cross-sectional area in the XY cross section becomes narrower toward the + Z direction side. The support column 7 is formed to have a main body portion 7A in contact with the first plate 4 and a head portion 7B located on the opposite side of the main body portion 7A from the first plate 4. The head portion 7B has a curved surface portion 7R that is convex in the + Z direction. The support column 7 is formed, for example, in a state where the height Ht in the Z direction is larger than the depth D of the recess 4a by Δ (μm).

The heating temperature in the heating furnace may be higher than the temperature at which the submicro copper particles 72a contained in the metal paste 70 are melted. It is known that the submicro copper particles 72a melt at a temperature of 400 ° C. or higher. On the other hand, the melting point of copper is about 1085 ° C. When the metal paste 70 is heated to near the melting point of copper, the micro copper particles 71 may also melt, making it difficult to obtain the support column 7 having the structure shown in FIG. Therefore, in the support column forming step S1, it is desirable to heat the metal paste 70 at a temperature of 400 ° C. or higher and 600 ° C. or lower. In particular, in the column forming step S1, it is desirable to heat the metal paste 70 at a temperature as low as 400 ° C. or higher.

In the support column forming step S1, the support column 7 may be formed by irradiating the metal paste 70 with a laser beam to heat the metal paste 70.

(5-2. Plane part forming process)
In the flat surface portion forming step S2, a part of the curved surface portion 7R of the head portion 7B of the support column 7 is cut using a cutter, a cutting tool, a cutting device, or the like to form the flat surface portion 7F. The flat surface portion 7F may be formed on a part of the curved surface portion 7R by pressing a part of the curved surface portion 7R with a jig or polishing with a polishing machine. That is, in the method of manufacturing the vapor chamber 1 of the present embodiment, a part of the curved surface portion 7R of the head portion 7B located on the opposite side of the first plate 4 with respect to the main body portion 7A of the support column 7 is processed to form a flat surface. The flat portion forming step S2 for forming the portion 7F is included.

Further, in the flat surface portion forming step S2, a part of the curved surface portion 7R is processed by cutting, pressing, or polishing to form the flat surface portion 7F. By processing a part of the curved surface portion 7R in this way to form the flat surface portion 7F, the portion of the head portion 7B of the support column 7 that protrudes from the recess 4a by Δ (μm) in the + Z direction is removed. Thereby, as shown in FIG. 4, the height Ht of the support column 7 can be made to match the depth D of the recess 4a. The flat surface portion forming step S2 is also referred to as a "secondary step" with respect to the above primary step.

(5-3. Joining process)
In the joining step S3, the second plate 5 is arranged and joined on the first plate 4 so as to form a housing 1a having a space 1b inside, and the support column 7 and the working medium 2 are formed in the housing 1a (FIG. FIG. 1) and seal. As a result, the vapor chamber 1 is completed. At this time, the second plate 5 is arranged so as to face the flat surface portion 7F of the support column 7, and the second plate 5 and the first plate 4 are connected to each other. As a result, in the recess 4a, the flat surface portion 7F of the support column 7 is positioned in contact with the second plate 5.

That is, in the method of manufacturing the vapor chamber 1, the second plate 5 is arranged so as to face the flat surface portion 7F, the second plate 5 and the first plate 4 are connected to each other, and the support column 7 is positioned in the recess 4a. Including the process.

The joining of the first plate 4 and the second plate 5 in the joining step S3 is performed by, for example, hot pressing. The joining step S3 may be performed by diffusion joining or brazing. Further, in the joining step S3, after the actuating medium 2 is injected, a step of sealing the injection port by welding is also performed.

(6. Effect)
As described above, in the present embodiment, the head portion 7B of the support column 7 has a flat surface portion 7F facing the second plate 5. The flat surface portion 7F is easily formed by a method such as cutting, pressing, or polishing as described above. Therefore, for example, when the support column 7 is formed in the recess 4a of the first plate 4 (primary step), as shown in FIG. 8, even if the height Ht of the support column 7 is larger than the depth D of the recess 4a, that is, Even if the apex 7p located on the + Z direction side of the curved surface portion 7R of the head portion 7B of the support column protrudes from the recess 4a to the second plate 5 side, a part of the curved surface portion 7R is cut to form the flat surface portion 7F. By performing the secondary step of forming, as shown in FIG. 4, it becomes possible to match the height Ht of the support column 7 with the depth D of the recess 4a. Therefore, in the primary process, it is not necessary to control the height Ht of the support column 7 with high accuracy. As a result, the productivity of the vapor chamber 1 can be improved.

Further, since the head portion 7B of the support column 7 has the curved surface portion 7R, the gap formed between the curved surface portion 7R and the second plate 5 becomes a flow path through which the working medium 2 (for example, steam) passes. Therefore, in the housing 1a, the steam generated on the heated portion 101 side can be efficiently guided to the heat radiating portion 102 side, and the heat can be efficiently transported by the movement of the working medium 2.

Further, the method for manufacturing the vapor chamber 1 of the present embodiment includes the above-mentioned support column forming step S1, the flat surface portion forming step S2, and the joining step S3. Even if the height Ht of the support column 7 is larger than the depth of the recess 4a in the support column forming step S1 which is the primary step, the support column is formed by forming the flat surface portion 7F on the support column 7 in the flat surface portion forming step S2 which is the secondary step. The height Ht of 7 and the depth of the recess 4a can be matched. Therefore, in the primary process, the productivity of the vapor chamber 1 can be improved without controlling the height Ht of the columns 7 with high accuracy.

In particular, in the flat surface portion forming step S2, a part of the curved surface portion 7R of the support column 7 is processed by a method such as cutting to form the flat surface portion 7F. Thereby, a part of the curved surface portion 7R can be easily processed to easily form the flat surface portion 7F.

(7. Other manufacturing methods of vapor chamber)
FIG. 9 is a cross-sectional view showing another manufacturing process of the vapor chamber 1. In the flat surface portion forming step S2, the flat surface portion 7F may be formed on the support column 7 by using the second plate 5. Specifically, the second plate 5 is pressed against the curved surface portion 7R of the head portion 7B of the support column 7 formed in the support column forming step S1 from the + Z direction side. Then, the second plate 5 is pressed toward the −Z direction. As a result, a part of the curved surface portion 7R is crushed to form the flat surface portion 7F. After that, the second plate 5 may be joined to the first plate 4 by hot pressing or the like.

As described above, in the flat surface portion forming step S2, the flat surface portion 7F is formed by pressing the second plate 5 against the curved surface portion 7R. Since the flat surface portion 7F is formed by using the second plate 5 instead of the jig, the flat surface portion forming step S2 can be simplified. That is, the step of pressing the curved surface portion 7R using a pressing jig other than the second plate 5 can be deleted. Thereby, the productivity of the vapor chamber 1 can be further improved.

By the way, when the second plate 5 is pressed against the curved surface portion 7R of the support column 7 to form the flat surface portion 7F, a part of the curved surface portion 7R is crushed as described above. Therefore, the porosity of the head portion 7B having the curved surface portion 7R is lower than the porosity of the main body portion 7A. That is, the porosity of the head portion 7B of the support column 7 is smaller than the porosity of the main body portion 7A. For example, when the height Ht of the support column 7 before pressing with the second plate 5 is 150 μm and the height Ht of the support column 7 after pressing with the second plate 5 is 120 μm, the porosity of the head 7B. Was 41%, and the porosity of the main body 7A was 54%, as a result of the simulation. Even when the curved surface portion 7R is pressed to form the flat surface portion 7F by using a pressing jig instead of the second plate 5, the porosity of the head portion 7B is the void of the main body portion 7A as described above. It turned out to be smaller than the rate.

Therefore, conversely, if the porosity of the head portion 7B is smaller than the porosity of the main body portion 7A, after performing the primary step of forming the support column 7 on the first plate 4, a part of the curved surface portion 7R is used as the first plate. It can be said that the head 7B was crushed by pressing from the opposite side to the first plate 4 side, that is, a part of the curved surface portion 7R was processed by pressing to form the flat portion 7F on the head 7B. .. By forming the flat surface portion 7F by the pressing process in this way, the flat surface portion 7F can be easily formed, and the support column 7 having the flat surface portion 7F can be easily realized.

(8. Other configurations of vapor chamber)
The vapor chamber 1 of the present embodiment is not limited to the configuration shown in FIG. FIG. 10 is a cross-sectional view schematically showing another configuration of the vapor chamber 1. As shown in the figure, the first plate 4 may be formed of a flat plate, and the second plate 5 may have a recess 5a recessed in the + Z direction. That is, the housing 1a may be formed by connecting the first plate 4 of the flat plate and the second plate 5 having a concave shape at the end portions.

In this configuration, in the housing 1a, the support column 7 is located in the recess 5a of the second plate 5. The height of the column 7 in the Z direction coincides with the depth of the recess 5a of the second plate 5 in the Z direction. Also in such a vapor chamber 1, the configuration of FIG. 4 in which the flat surface portion 7F is formed on the head portion 7B of the support column 7 can be applied. As a result, in the primary process, the productivity of the vapor chamber 1 can be improved without controlling the height Ht of the columns 7 with high accuracy, and the same effects as those of the present embodiment can be obtained.

FIG. 11 is a cross-sectional view schematically showing still another configuration of the vapor chamber 1 of the present embodiment. As shown in the figure, the first plate 4 may have a recess 4a recessed in the −Z direction, and the second plate 5 may have a recess 5a recessed in the + Z direction. That is, both the first plate 4 and the second plate 5 may be formed in a concave shape. Then, the concave first plate 4 and the concave second plate 5 are connected at the ends to form the housing 1a, and the concave portion 4a and the concave portion 5a form a space 1b of the housing 1a. May be good.

In this configuration, in the housing 1a, the columns 7 are located across both the recess 4a of the first plate 4 and the recess 5a of the second plate 5. The height of the column 7 in the Z direction coincides with the sum of the depth of the recess 4a of the first plate 4 in the Z direction and the depth of the recess 5a of the second plate 5 in the Z direction. Also in such a vapor chamber 1, the configuration of FIG. 4 in which the flat surface portion 7F is formed on the head portion 7B of the support column 7 can be applied. As a result, in the primary process, the productivity of the vapor chamber 1 can be improved without controlling the height Ht of the columns 7 with high accuracy, and the same effects as those of the present embodiment can be obtained.

FIG. 12 is a cross-sectional view schematically showing still another configuration of the vapor chamber 1 of the present embodiment. As shown in the figure, the vapor chamber 1 may further have a wick material 3 in the housing 1a. The wick material 3 is formed in a sheet shape and is located on the surface 1c on the + Z direction side of the first plate 4. That is, the vapor chamber 1 further has a wick material 3, which is located on the surface 1c of the first plate 4 facing the second plate 5. The thickness of the wick material 3 is, for example, 0.02 mm or less. The wick material 3 has a porous wick structure made of, for example, a copper sintered body. The surface 1c is here the inner bottom surface of the first recess 4a.

The wick material 3 may have a structure capable of internally transporting the working medium 2 by a capillary phenomenon. Therefore, the wick material 3 includes, in addition to the above-mentioned porous wick structure (sintered wick), a mesh wick made of a metal mesh, a groove wick having a groove structure, and the like.

In the configuration of FIG. 12, the working medium 2 flows not only in the support column 7 but also in the sheet-shaped wick material 3 by the capillary phenomenon in the housing 1a. Thereby, the heat transport efficiency due to the movement of the working medium 2 in the housing 1a can be further improved.

In particular, the wick material 3 has a wick structure. Thereby, the wick material 3 can be integrally formed with the support column 7 having the wick structure. Therefore, the vapor chamber 1 including the support column 7 and the wick material 3 can be easily manufactured.

Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to this, and various modifications can be made without departing from the gist of the invention. Further, the above-described embodiment and its modifications can be arbitrarily combined.

The heat conductive member of the present invention can be used, for example, as a member for heat dissipation of a substrate or an electronic component mounted on an electronic device.

1 Vapor chamber (heat conductive member)
1a Housing 1b Space 1c Inner surface 2 Operating medium 3 Wick material 4 1st plate 4a Recess 5 2nd plate 5a Recess 7 Support 7A Main body 7B Head 7F Flat surface 7R Curved surface

Claims (7)

A housing that houses the working medium and has a space inside,
A heat conductive member comprising at least one support column located in the housing.
The housing has a first plate and a second plate arranged opposite to each other.
At least one of the first plate and the second plate has a recess and has a recess.
The strut is located in the recess and
The support is
The main body in contact with the first plate and
It has a head located on the opposite side of the first plate with respect to the main body portion, and has.
The head is
A flat surface portion facing the second plate and
A heat conductive member having a curved surface portion connected to the flat surface portion. The column has a porous wick structure and has a porous wick structure.
The heat conductive member according to claim 1, wherein the porosity of the head of the column is smaller than the porosity of the main body. Has more wick material,
The heat conductive member according to claim 2, wherein the wick material is located on a surface of the first plate facing the second plate. The heat conductive member according to claim 3, wherein the wick material has the wick structure. A strut forming step of forming a strut on the first plate using a first plate and a second plate having at least one recess.
A flat surface forming step of forming a flat surface portion by processing a part of the curved surface portion of the head located on the opposite side of the first plate to the main body portion of the support column.
A heat conductive member comprising a joining step of arranging the second plate facing the flat surface portion, connecting the second plate and the first plate, and locating the support column in the recess. Manufacturing method. The method for manufacturing a heat conductive member according to claim 5, wherein in the flat surface forming step, a part of the curved surface portion is processed by cutting, pressing, or polishing to form the flat surface portion. The method for manufacturing a heat conductive member according to claim 5, wherein in the flat portion forming step, the flat portion is formed by pressing the second plate against the curved surface portion.

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