A large flat heat spreader with a composite liquid wick

Abstract

The present invention relates to a large flat heat spreader with a composite liquid wick, comprising an upper cover plate and a lower cover plate which are connected in a peripheral sealing manner to form a sealed working medium cavity, wherein the sealed working medium cavity is in a vacuum state and is filled with a liquid working medium, wherein the upper cover plate is provided with a first area and a second area, wherein the first area is close to an evaporation end and is provided with a plurality of densely arranged first support columns, and the second area is provided with a plurality of sparsely arranged second support columns, wherein a second liquid wick is placed in the gaps between the second support columns; wherein the lower cover plate is provided with a third area and a fourth area, wherein the size of the third area corresponds to that of the first area and is used for placing the first liquid wick; wherein the size of the fourth area corresponds to that of the second area and is provided with sparsely arranged third support columns, wherein the number and arrangement of the third support columns correspond to those of the second support columns, and the problems of insufficient steam flow space, poor heat transfer performance and poor structural strength in the large flat heat spreader can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of hot plate design and manufacturing, and in particular relates to a large-plane heat spreader with a composite liquid-absorbing core. Background Art

[0002] At present, various structural forms of vapor chambers have been proposed. As vapor chambers develop towards large surfaces and ultra-thinness, multiple design challenges must be considered comprehensively. In the design process, the following problems usually exist: insufficient steam flow space, weak capillary force of the liquid absorption core, or insufficient overall structural strength. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a large flat vapor chamber with a composite liquid absorbent core in view of the deficiencies of the above-mentioned prior art. The vapor chamber of the present invention adopts a composite liquid absorbent core with different liquid absorbent core materials and structural forms, and cooperates with the evaporation zone and condensation zone of the vapor chamber, which can effectively solve the problems of insufficient steam flow space, poor heat transfer performance and insufficient structural strength in the ultra-thin large flat vapor chamber. The present invention optimizes the design of the vapor chamber liquid absorbent core structure and supporting structure, provides the steam space to a greater extent and ensures the overall structural strength and temperature uniformity of the vapor chamber. This invention is particularly suitable for large flat vapor chambers with an area greater than 40mm*40mm.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: a large flat heat spreader of a composite liquid wick, comprising an upper cover plate and a lower cover plate which are sealed and connected at the periphery to form a sealed working medium cavity, wherein the sealed working medium cavity is in a vacuum state and is filled with a liquid working medium, wherein the upper cover plate is provided with a first area and a second area, wherein the first area is close to the evaporation end and is provided with a plurality of densely arranged first support columns, and the second area is provided with a plurality of sparsely arranged second support columns, wherein a second liquid wick is placed in the gaps between the second support columns;

[0005] The lower cover plate is provided with a third area and a fourth area, wherein the size of the third area corresponds to that of the first area and is used to place the first liquid absorbent core; the size of the fourth area corresponds to that of the second area and is provided with sparsely arranged third support columns, and the number and arrangement of the third support columns correspond to those of the second support columns.

[0006] Furthermore, the first absorbent core is an absorbent core with a sintered or metal fiber capillary structure, and the second absorbent core is an absorbent core with a linear or long metal fiber or sintered capillary structure. The second absorbent core overlaps the first absorbent core at the boundary to ensure good contact.

[0007] Furthermore, the upper surface of the first liquid absorbent core is in contact with the first support column, and the lower surface is in contact with the concave surface of the lower cover plate, and the thickness is equal to the thickness of the concave surface of the lower cover plate, and the size is equivalent to the area of ​​the heat source.

[0008] Furthermore, the upper surface of the second liquid absorbent core is in contact with the lower surface of the upper cover plate, and the lower surface is in contact with the upper surface of the lower cover plate. The thickness of the second liquid absorbent core is equal to the total thickness of the sealed working medium cavity.

[0009] Furthermore, the second liquid wick extends from the evaporation end to the condensation end of the vapor chamber, and has a cross-sectional thickness greater than that of the first liquid wick.

[0010] Furthermore, the third region is subjected to surface roughening treatment, using physical methods including nanosecond laser processing to form a continuous capillary structure with a hairy morphology on the surface; or the surface is corroded by chemical or electrochemical methods to form a hydrophilic porous structure; or the surface is roughened by thermal oxidation.

[0011] Furthermore, the wall materials of the upper cover plate and the lower cover plate are made of high-strength and lightweight materials including copper, stainless steel, titanium or titanium alloy, aluminum or aluminum alloy, magnesium or magnesium alloy. When the wall material is stainless steel, titanium or titanium alloy, the inner walls of the upper cover plate and the lower cover plate are respectively plated with a second material layer and a third material layer to form a composite wall material, wherein the second material layer is a nickel plating layer, a titanium plating layer, a zinc plating layer or a chromium plating layer, and the third material layer is a copper plating layer.

[0012] Furthermore, the wall thickness of the upper cover plate and the lower cover plate is 0.1-0.3 mm, and the lower surface of the upper cover plate is etched with a concave surface with a plurality of regularly arranged support columns, which serves as a steam chamber.

[0013] Furthermore, the first absorbent core is overlapped with the second absorbent core through a plurality of small grooves arranged at the boundary to form a composite absorbent core, and the composite absorbent core is subjected to a hydrophilic treatment.

[0014] Furthermore, the outer peripheries of the upper cover plate and the lower cover plate are combined into one by diffusion welding, and the second support column and the third support column are combined into one by welding.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) The wall materials of the upper cover plate and the lower cover plate of the heat spreader of the present invention are made of high-strength and lightweight materials, such as copper, stainless steel, titanium or titanium alloy, aluminum or aluminum alloy, magnesium or magnesium alloy, etc. When the wall material is stainless steel, titanium or titanium alloy, the inner wall is plated with a second layer of material and a third layer of material to form a composite wall material. The second material layer is a nickel plating layer, a titanium plating layer, a zinc plating layer or a chromium plating layer, etc.; the third material layer is a copper plating layer. The wall material can ensure the strength of the plate body, the second layer of material ensures the uniformity and firmness of the copper plating, and the innermost copper plating ensures the hydrophilicity of the wall.

[0017] (2) The heat spreader of the present invention adopts a composite wick to solve the problem of insufficient capillary force and insufficient steam space of the large flat heat spreader. The composite wick is composed of a first wick and a second wick. The composite wick is treated to be hydrophilic, such as magnetron sputtering titanium dioxide, thermal oxidation or plasma cleaning, to enhance the hydrophilicity of foam copper or copper wire. The first wick is a sintered capillary structure or a metal fiber capillary structure, such as foam copper or a woven copper mesh, and its plane size is equivalent to the heat source area, and is placed at the evaporation end in the cavity of the heat spreader. The second wick is a linear or long strip of metal fiber or a sintered capillary structure, such as a copper wire or a long strip of foam copper or a long strip of copper mesh, extending from the evaporation end to the far end of the heat spreader. The second wick overlaps the boundary of the first wick structure to ensure good contact.

[0018] (3) The thickness of the first liquid-absorbing core of the present invention is equal to the thickness of the concave surface of the lower cover plate, its lower surface is in contact with the concave surface of the lower cover plate, and its upper surface is in contact with the support column of the upper cover plate. Its plane size is equivalent to the area of ​​the heat source and is placed in the third area of ​​the concave surface of the lower cover plate. The temperature at the evaporation end is high and the evaporation rate is fast. The first liquid-absorbing core with high porosity and strong capillary force can store enough water to prevent the evaporation end from drying out.

[0019] (4) The thickness of the second liquid absorbent core of the present invention is equal to the total thickness of the upper and lower cavities of the heat spreader, its upper surface is in contact with the lower surface of the upper cover, and its lower surface is in contact with the upper surface of the lower cover. The second liquid absorbent core extends from the evaporation end to the condensation end of the heat spreader, and its cross-sectional thickness is greater than that of the first liquid absorbent core, thereby ensuring sufficient capillary force to help the condensation end to quickly return water.

[0020] (5) The present invention performs surface roughening treatment on the first area of ​​the lower cover plate. The surface roughening treatment process is simple and low-cost. It can not only solve the problem of insufficient capillary force but also save materials, making the heat spreader lighter and thinner as a whole.

[0021] (6) The upper and lower cover plates of the present invention are combined into one by diffusion welding, the outer peripheries of the upper and lower cover plates are welded together, the second support column in the second area of ​​the upper cover plate and the third support column in the fourth area of ​​the lower cover plate are welded together, and the entirety of the heat spreader is effectively connected everywhere, having better structural strength and compressive and tensile resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a structural exploded view of the large flat heat spreader of the composite liquid absorbent core of the present invention.

[0023] Figure 2 It is a schematic diagram of the relative positions of the liquid wick of the heat spreader and the lower cover plate of the present invention.

[0024] Figure 3 It is a schematic cross-sectional view of the steam channel of the heat diffusion plate of the present invention.

[0025] Figure 4 It is a schematic diagram of the diffusion welding combination of the heat spreader of the present invention.

[0026] Explanation of the reference numerals: 1-upper cover plate; 2-lower cover plate; 3-sealed working medium chamber; 11-first area; 12-second area; 21-third area; 22-fourth area; 41-first support column; 42-second support column; 43-third support column; 51-first liquid absorbent core; 52-second liquid absorbent core; I-primary steam channel; II-secondary steam channel. DETAILED DESCRIPTION

[0027] The specific implementation of the present invention is described in detail below in conjunction with the technical solution (and drawings).

[0028] Example 1

[0029] A large flat heat spreader with a composite liquid wick, comprising an upper cover plate 1 and a lower cover plate 2 which are sealed and connected to form a sealed working medium chamber 3, wherein the sealed working medium chamber 3 is in a vacuum state and is filled with a liquid working medium, and the upper cover plate 1 is provided with a first area 11 and a second area 12, wherein the first area 11 is close to the evaporation end and is provided with a plurality of densely arranged first support columns 41, and the second area 12 is provided with a plurality of sparsely arranged second support columns 42, wherein a second liquid wick 52 is placed in the gaps between the second support columns 42;

[0030] The lower cover plate 2 is provided with a third area 21 and a fourth area 22, wherein the size of the third area 21 corresponds to that of the first area 11 and is used to place the first liquid absorbent core 51; the size of the fourth area 22 corresponds to that of the second area 12 and is provided with sparsely arranged third support columns 43, and the number and arrangement of the third support columns 43 correspond to those of the second support columns 42.

[0031] The upper surface of the first liquid wick 51 is in contact with the first support column 41, and the lower surface is in contact with the concave surface of the lower cover plate 2. The thickness is equal to the thickness of the concave surface of the lower cover plate 2, and the size is equivalent to the heat source area. The first liquid wick 51 is made of foam copper with a thickness of 0.07 mm. The temperature at the evaporation end is high and the evaporation rate is fast. The foam copper liquid wick with high porosity and strong capillary force can store enough water to prevent the evaporation end from drying out.

[0032] The upper surface of the second liquid absorbent core 52 is in contact with the lower surface of the upper cover plate 1, and the lower surface is in contact with the upper surface of the lower cover plate 2. The second liquid absorbent core 52 is a copper wire liquid absorbent core with a thickness of 0.15 mm, which is equal to the total thickness of the sealed working medium chamber 3. The second liquid absorbent core 52 extends from the evaporation end of the heat spreader to the condensation end, and the cross-sectional thickness is greater than that of the first liquid absorbent core 51. The copper wire can effectively save space in terms of area, saving a steam channel with a larger cross-sectional thickness, and the copper wire itself has a certain structural strength, which plays a supporting role for the heat spreader cavity. The composite liquid absorbent core composed of foam copper and copper wire not only ensures the water storage capacity and sufficient capillary force at the evaporation end, but also enables the condensed water at the far end to quickly flow back, and has a certain structural support effect. It is particularly suitable for ultra-thin heat spreaders with large planes.

[0033] The first absorbent core 51 is overlapped with the second absorbent core 52 through a plurality of small grooves arranged at the boundary to form a composite absorbent core, and the composite absorbent core is subjected to a hydrophilic treatment, such as magnetron sputtering titanium dioxide coating, thermal oxidation or plasma cleaning, to enhance the hydrophilicity of the foamed copper or copper wire. In this example, the hydrophilic treatment is performed by magnetron sputtering titanium dioxide coating.

[0034] The third region 21 is subjected to surface roughening treatment, and its surface is roughened by a nanosecond laser processing device to form a continuous capillary structure with a hairy morphology. The surface roughening treatment process is simple and low-cost. It can not only solve the problem of insufficient capillary force, but also save materials, making the overall heat spreader lighter and thinner.

[0035] The wall materials of the upper cover plate 1 and the lower cover plate 2 are both made of a stainless steel-nickel-copper three-layer composite material of stainless steel plated with nickel and then plated with copper. The wall thickness of the upper cover plate 1 is 0.13 mm, and a concave surface with several regularly arranged support columns is etched on the lower surface of the upper cover plate 1 by chemical corrosion, which serves as a steam chamber; the wall thickness of the lower cover plate 2 is 0.12 mm, and a flat foam copper liquid wick is placed in the third area 21 located at the evaporation end, and the fourth area 22 outside the evaporation end corresponds to the second area 12, and the gaps between the support columns are used to place several copper wire liquid wicks. Stainless steel can ensure the strength of the plate body, the middle nickel plating layer ensures the uniformity and firmness of the copper plating, and the innermost copper plating ensures the hydrophilicity of the wall.

[0036] The outer periphery of the upper cover plate 1 and the lower cover plate 2 are combined into one by diffusion welding, and the second support column 42 and the third support column 43 are combined into one by welding. The entirety of the heat spreader is effectively connected everywhere, and has better structural strength and compression and tension resistance.

[0037] Example 2

[0038] A large flat heat spreader with a composite liquid wick, comprising an upper cover plate 1 and a lower cover plate 2 which are sealed and connected to form a sealed working medium chamber 3, wherein the sealed working medium chamber 3 is in a vacuum state and is filled with a liquid working medium, and the upper cover plate 1 is provided with a first area 11 and a second area 12, wherein the first area 11 is close to the evaporation end and is provided with a plurality of densely arranged first support columns 41, and the second area 12 is provided with a plurality of sparsely arranged second support columns 42, wherein a second liquid wick 52 is placed in the gaps between the second support columns 42;

[0039] The lower cover plate 2 is provided with a third area 21 and a fourth area 22, wherein the size of the third area 21 corresponds to that of the first area 11 and is used to place the first liquid absorbent core 51; the size of the fourth area 22 corresponds to that of the second area 12 and is provided with sparsely arranged third support columns 43, and the number and arrangement of the third support columns 43 correspond to those of the second support columns 42.

[0040] The upper surface of the first absorbent core 51 is in contact with the first support column 41, and the lower surface is in contact with the concave surface of the lower cover plate 2. The thickness is equal to the thickness of the concave surface of the lower cover plate 2, and the plane size is equivalent to the heat source area. The first absorbent core 51 is a woven copper mesh with a thickness of 0.08 mm.

[0041] The upper surface of the second liquid absorbent core 52 is in contact with the lower surface of the upper cover plate 1, and the lower surface is in contact with the upper surface of the lower cover plate 2. The second liquid absorbent core 52 is a long strip of foam copper with a thickness of 0.2 mm, which is equal to the total thickness of the sealed working medium chamber 3. The second liquid absorbent core 52 extends from the evaporation end of the heat spreader to the condensation end, and the cross-sectional thickness is greater than that of the first liquid absorbent core 51, thereby ensuring sufficient capillary force to help the condensation end to quickly return water.

[0042] The first absorbent core 51 is overlapped with the second absorbent core 52 through a plurality of small grooves arranged at the boundary to form a composite absorbent core, and the composite absorbent core is subjected to a hydrophilic treatment, such as magnetron sputtering titanium dioxide coating, thermal oxidation or plasma cleaning, to enhance the hydrophilicity of the foam copper or copper wire. In this example, the hydrophilic treatment is performed by plasma cleaning.

[0043] The third region 21 is subjected to a surface roughening treatment, and its surface is corroded by a chemical method to construct a hydrophilic porous structure on its surface.

[0044] The wall materials of the upper cover plate 1 and the lower cover plate 2 are both made of a titanium-nickel-copper three-layer composite material in which titanium is plated with nickel and then plated with copper. The wall thickness of the upper cover plate 1 is 0.2 mm. A concave surface with a number of regularly arranged support columns is etched on the lower surface of the upper cover plate 1 by chemical corrosion to serve as a steam chamber; the wall thickness of the lower cover plate is 0.15 mm.

[0045] The outer periphery of the upper cover plate 1 and the lower cover plate 2 are combined into one by diffusion welding, and the second support column 42 and the third support column 43 are combined into one by welding. The entirety of the heat spreader is effectively connected everywhere, and has better structural strength and compression and tension resistance.

[0046] The steam channel of the present application is composed of a primary steam channel I and a secondary steam channel II. The primary steam channel I includes the first area 11 of the upper cover plate of the evaporation zone and the third area 21 of the lower cover plate 2; the secondary steam channel II includes the second area 12 of the upper cover plate 1 and the fourth area 22 of the lower cover plate 2. After the steam evaporates on the surface of the first wick 51, it passes through the primary steam channel I with a support column on the upper part, and then flows to the secondary steam channel II around the second wick. On the flow path, the thickness cross-section of the steam chamber changes from small to large, and the thickness of the steam chamber increases, which can effectively reduce the heat transfer thermal resistance of the steam chamber and achieve good heat transfer performance.

[0047] Inside the heat spreader, the liquid medium exists in the composite liquid absorbent core. When it starts working, the liquid medium in the first liquid absorbent core 51 evaporates due to heat to form steam, and the steam passes through the primary steam channel I and the secondary steam channel II along the channels between the support columns, and the heat diffuses to the far end of the heat source. The liquid medium formed after the steam condenses flows back to the heat source position through the capillary force of the second liquid absorbent core 52, and the cycle continues. This ultra-thin heat spreader uses the principle of phase change heat transfer to effectively solve the heat dissipation problem of electronic components with high heat flux density in a small space.

[0048] The above is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent change made to the above embodiment according to the essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A large planar heat spreader of a composite liquid wick, comprising an upper cover plate (1) and a lower cover plate (2) which are connected in a peripheral sealing manner to form a sealed working medium chamber (3), wherein the sealed working medium chamber (3) is in a vacuum state and is filled with a liquid working medium, characterized in that: The upper cover plate (1) is provided with a first area (11) and a second area (12); the first area (11) is close to the evaporation end and is provided with a plurality of densely arranged first support columns (41); the second area (12) is provided with a plurality of sparsely arranged second support columns (42); second liquid wicks (52) are placed in the gaps between the second support columns (42); The lower cover plate (2) is provided with a third area (21) and a fourth area (22), wherein the size of the third area (21) corresponds to that of the first area (11) and is used to place the first liquid absorbent core (51); the size of the fourth area (22) corresponds to that of the second area (12) and is provided with sparsely arranged third support columns (43), and the number and arrangement of the third support columns (43) correspond to those of the second support columns (42); The first absorbent core (51) is an absorbent core with a sintered or metal fiber capillary structure, the second absorbent core (52) is an absorbent core with a linear or long strip metal fiber or sintered capillary structure, and the second absorbent core (52) overlaps the first absorbent core (51) at the boundary to ensure good contact; The upper surface of the first liquid absorbent core (51) is in contact with the first support column (41), and the lower surface is in contact with the concave surface of the lower cover plate (2). The thickness of the first liquid absorbent core (51) is equal to the thickness of the concave surface of the lower cover plate (2), and the size is equivalent to the area of ​​the heat source. The upper surface of the second liquid absorbent core (52) is in contact with the lower surface of the upper cover plate (1), and the lower surface is in contact with the upper surface of the lower cover plate (2); the thickness of the second liquid absorbent core (52) is equal to the total thickness of the sealed working fluid chamber (3); The second liquid wick (52) extends from the evaporation end to the condensation end of the vapor chamber, and has a cross-sectional thickness greater than that of the first liquid wick (51); The first liquid absorbent core (51) is overlapped with the second liquid absorbent core (52) via a plurality of small grooves arranged at the boundary to form a composite liquid absorbent core, and the composite liquid absorbent core is subjected to a hydrophilic treatment.

2. The large flat vapor chamber of the composite liquid wick according to claim 1, characterized in that: The third region (21) is subjected to a surface roughening treatment, using physical methods including nanosecond laser processing to form a continuous capillary structure with a hairy morphology on the surface; or using a chemical or electrochemical method to corrode the surface to form a hydrophilic porous structure; or using a thermal oxidation method to roughen the surface.

3. The large flat vapor chamber of the composite liquid wick according to claim 1, characterized in that: The wall materials of the upper cover plate (1) and the lower cover plate (2) are made of high-strength and lightweight materials including copper, stainless steel, titanium or titanium alloy, aluminum or aluminum alloy, magnesium or magnesium alloy. When the wall material is stainless steel, titanium or titanium alloy, the inner walls of the upper cover plate (1) and the lower cover plate (2) are respectively plated with a second material layer and a third material layer to form a composite wall material, wherein the second material layer is a nickel plating layer, a titanium plating layer, a zinc plating layer or a chromium plating layer, and the third material layer is a copper plating layer.

4. The large flat vapor chamber of the composite liquid wick according to claim 1, characterized in that: The wall thickness of the upper cover plate (1) and the lower cover plate (2) is 0.1-0.3 mm, and the lower surface of the upper cover plate (1) is etched with a concave surface with a plurality of regularly arranged support columns, serving as a steam chamber.

5. The large flat vapor chamber of the composite liquid wick according to claim 1, characterized in that: The outer peripheries of the upper cover plate (1) and the lower cover plate (2) are combined into one piece by diffusion welding, and the second support column (42) and the third support column (43) are combined into one piece by welding.

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