Vapor chamber design method, vapor chamber manufacturing method, and vapor chamber

Abstract

The vapor chamber (1) has a flat-plate-shaped housing (50) in which an internal space (20) is formed, and the housing (50) has formed therein: a heat-receiving section (3) that receives heat from a heat source body (2), a vapor flow path (5) through which a refrigerant (CO) vaporized in the heat-receiving section (3) moves, and a capillary flow path (4) through which the refrigerant (CO) liquefied by heat dissipation is conveyed to the heat-receiving section (3) by means of a capillary force. A plurality of spacers (42) for reinforcing the housing (50) are arranged in the internal space (20) along the surface direction of the housing (50). When [delta] c [mm] is the allowable amount of bending deformation of the housing (50), E [N / mm2] is the longitudinal elastic coefficient of the housing (50), I [mm2] is the moment of inertia of the cross section of the housing (50), and w [N / mm] is the uniform load applied to the housing (50) per unit length due to the internal pressure or external pressure generated in the internal space (20), [delta] c [mm] is the allowable amount of bending deformation of the housing (50), E [N / mm2] is the longitudinal elastic coefficient of the housing (50), I [mm2] is the moment of inertia of the cross section of the housing (50), and w [N / mm] is the uniform load. The distance (Lsp [mm]) between the spacers (42) and the joining protrusions (17) that are adjacent to each other is defined so as to satisfy the following formula.

Description

Technical Field

[0001] This invention relates to a design method for a heat spreader, a manufacturing method for a heat spreader, and a heat spreader itself. Background Technology

[0002] A heat spreader or flat heat pipe (hereinafter referred to as a heat spreader) that diffuses heat received from a cooled body in the planar direction achieves heat transfer by heating a refrigerant sealed in its internal space, causing a phase change, and circulating the refrigerant in both the planar and thickness directions. The liquefied refrigerant, heated in the heated section near the cooled body, evaporates and vaporizes, moving to the condenser section in both the planar and thickness directions due to the pressure difference within the internal space. Upon reaching the condenser section, the vaporized refrigerant releases heat and condenses, becoming liquefied. The liquefied refrigerant then moves back to the heated section due to capillary forces generated in the internal micro-flow paths (see, for example, Patent Document 1).

[0003] Patent Document 1: Japanese Patent No. 4035155

[0004] In electronic components such as semiconductor devices, the electrical power input that is not used for work is converted into heat, generating Joule heating. As the temperature of electronic components rises, their operating efficiency decreases and their lifespan shortens. Therefore, if the temperature rise can be suppressed, relatively high operating efficiency and long lifespan can be achieved.

[0005] Joule heat is conducted from the electronic components to the air or the mounting substrate on which the electronic components are mounted. Therefore, the degree of temperature rise of the electronic components themselves is influenced by the thermal conductivity of the mounting substrate. High thermal conductivity of the mounting substrate results in a smaller temperature rise for the electronic components, and vice versa. Therefore, mounting substrates with high thermal conductivity are required.

[0006] As a substrate with high thermal conductivity, a metal core substrate using a metal with high thermal conductivity, such as copper, is used. Copper has relatively high thermal conductivity as a metal, but even so, it is only 400 [W·m]. -1 K -1 Approximately [ ]. As a heat dissipation component with a higher thermal conductivity than metals such as copper, the aforementioned vapor chamber has attracted attention. This is because the vapor chamber is a latent heat transfer component that transfers heat through the phase change of the refrigerant sealed inside a container with an airtight structure, and it also has high thermal diffusivity.

[0007] Furthermore, in the process of mounting electronic components onto a mounting substrate, there is a reflow soldering process for surface mount components. In the reflow soldering process, solder is applied between the contacts of the circuitry formed on the substrate and the contacts of the components. The solder is then melted in a heating furnace, thereby simultaneously mounting multiple components onto the substrate. The substrate for mounting electronic components needs heat resistance to prevent deformation even when the temperature of the solder-coated portion during reflow soldering exceeds the melting point of the solder. However, generally, the heat resistance temperature of a vapor chamber is around 150°C, posing a problem with heat resistance during reflow soldering.

[0008] Furthermore, when a vapor chamber is used as a mounting substrate, a bonding process is performed to adhere the vapor chamber to the thin substrate by applying pressure. Therefore, vapor chambers with low mechanical strength to resist external stresses such as pressure are difficult to use as mounting substrates. In the vapor chamber disclosed in Patent Document 1, a reinforcing portion is formed in the internal space to achieve mechanical strength to resist the increase in internal pressure or the aforementioned external stresses as temperature rises. However, the reinforcing portion is only formed around the refrigerant inlet where the refrigerant is injected.

[0009] In addition to capillary forces and viscous forces, liquefied refrigerants are also affected by gravity. When the capillary force is not sufficiently greater than gravity, gravity becomes a resistance to the capillary force, depending on the orientation of the heat spreader, thus reducing the thermal performance of the heat spreader. It is desirable that the thermal performance of the heat spreader does not decrease even if its orientation is changed.

[0010] The environments in which equipment equipped with vapor chambers are set up vary, and the resistance acting on the liquefied refrigerant also varies depending on the environment. For example, when the vapor chamber is placed on a moving body undergoing acceleration, the inertial force based on the acceleration may also become a capillary force resistance. When the magnitude of the capillary force acting on the fluid mass of liquefied refrigerant is insufficient to overcome these resistances, the thermal performance of the vapor chamber decreases. Summary of the Invention

[0011] The present invention was made under the above-mentioned actual conditions, and its purpose is to provide a design method, a manufacturing method and a heat spreader plate capable of suppressing deformation caused by internal pressure rise accompanied by high heat or deformation caused by external force.

[0012] Furthermore, the present invention was made under the aforementioned actual conditions, and its purpose is to provide a design method, a manufacturing method, and a heat spreader capable of continuous heat diffusion with heat equal to or greater than that generated by the cooled body under conditions where thermal performance is not affected by resistance.

[0013] To achieve the above objectives, the design method of the heat spreader according to the first aspect of the present invention is executed by an information processing device, wherein...

[0014] The aforementioned heat spreader has a flat shell with an internal space.

[0015] The aforementioned shell is formed with:

[0016] The heated part receives heat from the cooled part;

[0017] A vapor flow path for the refrigerant that has vaporized in the aforementioned heated section; and

[0018] The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the aforementioned heated section via capillary force.

[0019] Multiple reinforcing members that reinforce the shell in the thickness direction are arranged along the surface direction of the shell in the internal space.

[0020] If the allowable amount of bending deformation of the aforementioned shell is set as δ c [mm], let the longitudinal elastic modulus of the above shell be E [N / mm] 2 Let the moment of inertia of the above-mentioned shell section be I [mm]. 2 Let w [N / mm] be the load per unit length of the shell caused by the internal or external pressure generated in the internal space, i.e., the uniformly distributed load. Then, let L be the spacing between the adjacent reinforcing members. sp [mm] is defined as satisfying the following formula:

[0021] [Mathematical Formula 1]

[0022] .

[0023] Alternatively, the capillary flow path described above may include a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchanger with a uniform grid spacing.

[0024] The aforementioned first micro-flow path has the following characteristics:

[0025] The straight pipe section unidirectionally transports the fluid block of the aforementioned refrigerant; and

[0026] The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path.

[0027] The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight pipe section is positive.

[0028] The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the aforementioned connecting part is positive.

[0029] The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive.

[0030] The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated part from the capillary flow path exceeds the heat input from the cooled body to the heated part per unit time.

[0031] The refrigerant and the material of the heat exchange plate are selected in such a way that all of the first, second, and fourth conditions are satisfied, or all of the first, third, and fourth conditions are satisfied, and the values ​​of the design parameters involved in the flow path structure of the capillary flow path are determined.

[0032] The design method for the heat spreader according to the second aspect of the present invention is executed by an information processing device, wherein...

[0033] The aforementioned heat spreader has a flat shell with an internal space.

[0034] The aforementioned shell is formed with:

[0035] The heated part receives heat from the cooled part;

[0036] A vapor flow path for the refrigerant that has vaporized in the aforementioned heated section; and

[0037] The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the aforementioned heated section via capillary force.

[0038] The aforementioned capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the aforementioned heat exchange plate with a uniform grid spacing.

[0039] The aforementioned first micro-flow path has the following characteristics:

[0040] The straight pipe section unidirectionally transports the fluid block of the aforementioned refrigerant; and

[0041] The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path.

[0042] The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight pipe section is positive.

[0043] The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the aforementioned connecting part is positive.

[0044] The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive.

[0045] The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated part from the capillary flow path exceeds the heat input from the cooled body to the heated part per unit time.

[0046] The refrigerant and the material of the housing are selected by satisfying all of the first, second, and fourth conditions, or by satisfying all of the first, third, and fourth conditions, and the values ​​of the design parameters involved in the flow path structure of the capillary flow path are determined.

[0047] Alternatively, in this case, the acceleration generated in the fluid block by the capillary force in the straight tube section can be set as a [m / s²]. 2 Let the density of the above fluid block be ρ [kg / m³]. 3 Let the volume of the fluid block mentioned above be V [m]. 3 Let the capillary force in the straight tube section be f. c [N], let F be the resistance that hinders the movement of the fluid block based on the capillary force described above. R When [N], the following expression is used as the conditional expression for the first condition mentioned above:

[0048] [Mathematical Formula 2]

[0049] ,

[0050] The capillary flow path described above includes a second micro-flow path that extends along the thickness direction of the housing and is arranged in two dimensions with uniform spacing in the surface direction of the housing.

[0051] The aforementioned connecting part includes:

[0052] The first connection portion not connected to the aforementioned second micro-flow path, and

[0053] The second connection portion connected to the aforementioned second micro-flow path,

[0054] Let a be the acceleration generated in the fluid block by the capillary force in the first connecting part. gap [m / s] 2 Let a be the acceleration generated in the fluid block by the capillary force in the second connection. gap．btm [m / s] 2 Let f be the capillary force generated in the first connecting part mentioned above. c．gap[N], let the capillary force generated in the second connecting part be f. c．gap．btm When [N], the following expression is used as the conditional expression for the second condition mentioned above:

[0055] [Mathematical Formula 3]

[0056] ,

[0057] Let L be the length of the straight pipe section in the direction of fluid block flow. DT [m], when the length of the connecting portion in the direction of the fluid block flow is set to 2W [m], and the ratio of the number of the first connecting portions to the number of connecting portions where the fluid block exists is set to ε, the following formula is used as the conditional expression for the third condition:

[0058] [Mathematical Formula 4]

[0059] ,

[0060] Let Q be the amount of heat input per unit time from the cooled body in the heated section. in [W], let Q be the latent heat of vaporization per unit mass of the above fluid block. LH [J / kg], where N is the number of the first micro-flow paths that are in contact with the outer edge of the heated part. 1．C The number of the second micro-flow paths connected to the heated part is set to N. 2．P Let S be the cross-sectional area of ​​the i-th micro-flow path that is orthogonal to the direction of fluid block flow and is connected to the outer edge of the heated part. A1．i [m] 2 Let S be the cross-sectional area of ​​the section of the j-th second micro-flow path that is orthogonal to the direction of fluid block flow that is connected to the heated part. A2．j [m] 2 The velocity of the fluid block flowing in the i-th first micro-flow path that is connected to the outer edge of the heated part is set as v. 1．i [m / s], where v is the velocity of the fluid block flowing in the j-th second micro-flow path connected to the heated section. 2．j When [m / s], the following expression is used as the conditional expression for the fourth condition mentioned above:

[0061] [Mathematical Formula 5]

[0062] ,

[0063] Where i is 1 to N 1．C A natural number, j is 1 to N 2．P The natural number.

[0064] Alternatively, the cross-section of the straight pipe section orthogonal to the direction of fluid block flow can be rectangular.

[0065] When the distance between the inner wall surfaces facing each other in the thickness direction of the straight pipe section is set to 2H [m], the distance between the inner wall surfaces facing each other in the surface direction of the straight pipe section is set to 2W [m], the surface tension of the fluid block relative to the inner wall surface is set to σ [N / m], and the contact angle between the fluid block and the inner wall surface is set to θ [rad],

[0066] The capillary force f generated in the fluid block in the aforementioned straight pipe section c [N] is defined by the following formula:

[0067] [Mathematical Formula 6]

[0068] ,

[0069] The capillary force f generated in the fluid block in the first connecting part mentioned above c．gap [N] is defined by the following formula:

[0070] [Mathematical Expression 7]

[0071] ,

[0072] The capillary force f generated in the fluid block in the second connecting part mentioned above c．gap．btm [N] is defined by the following formula:

[0073] [Mathematical Formula 8]

[0074] .

[0075] Alternatively, the length of the fluid block in the direction of fluid block flow can be set as h [m], and the spacing between the straight pipe sections in the direction of fluid block flow can be set as L. DP [m], where the shear stress generated on the inner wall surface along the thickness direction in the first micro-flow path is defined as τ. w．sp [Pa], where the shear stress generated on the inner wall surface along the aforementioned surface direction in the first micro-flow path is defined as τ. w．dp When [Pa],

[0076] The aforementioned resistance F R The viscous force f generated by the fluid mass flowing in the first micro-flow path. R1 [N] is defined by the following formula:

[0077] [Mathematical Expression 9]

[0078] .

[0079] Alternatively, the resistance that prevents the movement of the fluid block based on the capillary force may include at least one of gravity, inertial force, and electromagnetic force.

[0080] The third aspect of this invention relates to a method for manufacturing a heat spreader, wherein,

[0081] The aforementioned heat spreader has a flat shell with an internal space.

[0082] The aforementioned shell is formed with:

[0083] The heated part receives heat from the cooled part;

[0084] A vapor flow path for the refrigerant that has vaporized in the aforementioned heated section; and

[0085] The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the aforementioned heated section via capillary force.

[0086] Multiple reinforcing members that reinforce the shell in the thickness direction are arranged along the surface direction of the shell in the internal space.

[0087] If the allowable amount of bending deformation of the aforementioned shell is set as δ c [mm], let the longitudinal elastic modulus of the above shell be E [N / mm] 2 Let the moment of inertia of the above-mentioned shell section be I [mm]. 2 Let w [N / mm] be the load per unit length of the shell caused by the internal or external pressure generated in the internal space, i.e., the uniformly distributed load. Then, the spacing L between the adjacent reinforcing members is... sp [mm] The reinforcing member is formed in the internal space of the housing in a manner that satisfies the following formula:

[0088] [Mathematical Formula 10]

[0089] .

[0090] Alternatively, the capillary flow path described above may include a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchanger with a uniform grid spacing.

[0091] The aforementioned first micro-flow path has the following characteristics:

[0092] The straight pipe section unidirectionally transports the fluid block of the aforementioned refrigerant; and

[0093] The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path.

[0094] The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight pipe section is positive.

[0095] The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the aforementioned connecting part is positive.

[0096] The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive.

[0097] The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated part from the capillary flow path exceeds the heat input from the cooled body to the heated part per unit time.

[0098] The refrigerant and the material of the housing are selected in such a way that all of the first, second, and fourth conditions or all of the first, third, and fourth conditions are satisfied, and the values ​​of the design parameters involved in the flow path structure of the capillary flow path are determined.

[0099] The housing is formed from the material selected above, having a flow path structure of the capillary flow path based on the determined design parameters.

[0100] The selected refrigerant is sealed into the internal space of the housing.

[0101] The fourth aspect of this invention relates to a method for manufacturing a heat spreader, wherein,

[0102] The aforementioned heat spreader has a flat shell with an internal space.

[0103] The aforementioned shell is formed with:

[0104] The heated part receives heat from the cooled part;

[0105] A vapor flow path for the refrigerant that has vaporized in the aforementioned heated section; and

[0106] The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the aforementioned heated section via capillary force.

[0107] The aforementioned capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the aforementioned heat exchange plate with a uniform grid spacing.

[0108] The aforementioned first micro-flow path has the following characteristics:

[0109] The straight pipe section unidirectionally transports the fluid block of the aforementioned refrigerant; and

[0110] The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path.

[0111] The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight pipe section is positive.

[0112] The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the aforementioned connecting part is positive.

[0113] The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive.

[0114] The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated part from the capillary flow path exceeds the heat input from the cooled body to the heated part per unit time.

[0115] The refrigerant and the material of the housing are selected in such a way that all of the first, second, and fourth conditions or all of the first, third, and fourth conditions are satisfied, and the values ​​of the design parameters involved in the flow path structure of the capillary flow path are determined.

[0116] The housing is formed from the material selected above, having a flow path structure of the capillary flow path based on the determined design parameters.

[0117] The selected refrigerant is sealed into the internal space of the housing.

[0118] The fifth aspect of the present invention relates to a heat spreader having a flat shell with an internal space. The shell includes: a heating portion for receiving heat from a cooled object; a vapor flow path for moving refrigerant vaporized in the heating portion; and a capillary flow path for capillary force transporting refrigerant liquefied due to heat dissipation to the heating portion. Multiple reinforcing members, which reinforce the shell in the thickness direction, are arranged along the surface direction of the shell in the internal space.

[0119] If the allowable amount of bending deformation of the aforementioned shell is set as δ c [mm], let the longitudinal elastic modulus of the above shell be E [N / mm] 2 Let the moment of inertia of the above-mentioned shell section be I [mm]. 2 Let w [N / mm] be the load per unit length of the shell caused by the internal or external pressure generated in the internal space, i.e., the uniformly distributed load. Then, let L be the spacing between the adjacent reinforcing members.sp [mm] is defined as satisfying the following formula:

[0120] [Mathematical Formula 11]

[0121] .

[0122] Alternatively, the capillary flow path described above may include a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchanger with a uniform grid spacing.

[0123] The aforementioned first micro-flow path has the following characteristics:

[0124] The straight pipe section unidirectionally transports the fluid block of the aforementioned refrigerant; and

[0125] The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path.

[0126] The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight pipe section is positive.

[0127] The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the aforementioned connecting part is positive.

[0128] The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive.

[0129] The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated part from the capillary flow path exceeds the heat input from the cooled body to the heated part per unit time.

[0130] The refrigerant, the material of the heat spreader, and the flow path structure of the capillary flow path are all satisfied or all satisfied, including the first condition, the second condition, and the fourth condition.

[0131] The sixth aspect of the present invention relates to a heat spreader plate that is flat and has a flat shell with an internal space. The shell includes: a heating section for receiving heat from the cooled object; a vapor flow path for moving the refrigerant vaporized in the heating section; and a capillary flow path for capillary force transporting the refrigerant liquefied due to heat dissipation to the heating section.

[0132] The aforementioned capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the aforementioned heat exchange plate with a uniform grid spacing.

[0133] The aforementioned first micro-flow path has the following characteristics:

[0134] The straight pipe section unidirectionally transports the fluid block of the aforementioned refrigerant; and

[0135] The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path.

[0136] The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight pipe section is positive.

[0137] The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the aforementioned connecting part is positive.

[0138] The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive.

[0139] The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated part from the capillary flow path exceeds the heat input from the cooled body to the heated part per unit time.

[0140] The refrigerant, the material of the housing, and the flow path structure of the capillary flow path are provided to satisfy all of the first, second, and fourth conditions or all of the first, third, and fourth conditions.

[0141] According to the present invention, deformation caused by internal pressure rise due to high heat or deformation caused by external force can be suppressed.

[0142] According to the present invention, in a two-dimensional grid-like flow path that generates capillary force with uniform grid spacing, the capillary force applied to the fluid block of the refrigerant exceeds the resistance that hinders the movement of the fluid block, and the work done by the force applied to the fluid block is positive all the time. It is possible to select the materials of the refrigerant and the heat spreader in a way that prevents drying in the heated part, and to determine the values ​​of the design parameters involved in the flow path structure of the capillary flow path. Therefore, continuous heat diffusion can be carried out without the thermal performance being affected by resistance. Attached Figure Description

[0143] Figure 1A This is a side view of the heat spreader according to an embodiment of the present invention.

[0144] Figure 1B yes Figure 1A A three-dimensional view of the heat spreader.

[0145] Figure 1C This is a side view of a modified example of a heat spreader according to an embodiment of the present invention.

[0146] Figure 1D yes Figure 1C A three-dimensional view of the heat spreader.

[0147] Figure 2A It constitutes Figure 1A and Figure 1B A three-dimensional view of the heat pipe components.

[0148] Figure 2B It constitutes Figure 1C and Figure 1D A three-dimensional view of the heat pipe components.

[0149] Figure 3A This is a top view of the lower component.

[0150] Figure 3B This is a magnified view of a portion of the internal area of ​​the lower component.

[0151] Figure 3C This is a top view of a modified example of the lower component.

[0152] Figure 4A This is a top view of the middle component.

[0153] Figure 4B This is a magnified view of a portion of the capillary flow path formation area in the intermediate component.

[0154] Figure 4C This is a top view of a modified example of the intermediate component.

[0155] Figure 5A This is a schematic diagram showing the internal space of the heat spreader as observed in the thickness and surface directions.

[0156] Figure 5B This is a schematic diagram showing the internal space of a deformed example of a heat spreader as observed in the thickness and surface directions.

[0157] Figure 6A This is a diagram showing an example of the configuration of the capillary flow path (first micro-flow path) formed in the lower component.

[0158] Figure 6B This is a diagram showing an example of the configuration of a capillary flow path (first micro-flow path).

[0159] Figure 6C This is a diagram showing the capillary flow path from the side.

[0160] Figure 7A This is a first schematic diagram showing the construction of the first micro-flow path.

[0161] Figure 7B This is a second schematic diagram illustrating the construction of the first micro-flow path.

[0162] Figure 8A This is the first schematic diagram representing the first and second conditions.

[0163] Figure 8B This is a second schematic diagram representing the first and second conditions.

[0164] Figure 9 This is a diagram representing the third condition.

[0165] Figure 10A This is a first schematic diagram showing the inflow of heat and the movement of refrigerant in the heated section.

[0166] Figure 10B This is a second schematic diagram illustrating the inflow of heat and the movement of refrigerant in the heated section.

[0167] Figure 11A It is a block diagram representing the hardware structure of an information processing device that performs design processing.

[0168] Figure 11B It is a flowchart of the design process.

[0169] Figure 12 It has Figure 1A A top view of the heat spreader plate used as the mounting base for the lighting device.

[0170] Figure 13A It is an exploded perspective view of a portion of the structure on the mounting surface of the mounting base plate in a lighting device.

[0171] Figure 13B This is a cross-sectional view showing the connection status of an LED on a mounting substrate.

[0172] Figure 14 Yes Figure 1A A chart comparing the junction temperatures of LED components in a heat spreader and a copper substrate.

[0173] Figure 15A This is a side view showing the vapor chamber set in a first orientation.

[0174] Figure 15B This is a side view showing the vapor chamber set in a second orientation.

[0175] Figure 15C This is a side view showing the vapor chamber set in a third orientation.

[0176] Figure 16 This is a graph showing the comparison results of thermal resistance when the orientation of the heat spreader is changed. Detailed Implementation

[0177] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same or equivalent parts are labeled with the same reference numerals.

[0178] [Implementation Method 1]

[0179] First, Embodiment 1 of the present invention will be described. For example... Figure 1A and Figure 1B As shown, the heat spreader 1 in this embodiment is a cooling device having a shell 50 that is generally flat, specifically circular, in the thickness direction along the z-axis. The shape of the shell 50 is not limited to a circular shape; for example, it can also be... Figure 1C and Figure 1D The image shown is a rectangular flat plate. Below, regardless of... Figure 1A and Figure 1B The shape shown is still Figure 1C and Figure 1D All shapes shown are of the heat spreader plate 1. Components with the same function are described using the same reference numerals. The housing 50 is made of a material capable of forming an airtight structure. Such a material is, for example, copper. A circular plate-shaped heat source 2, which is the object to be cooled, is mounted at the center of the bottom surface of the heat spreader plate 1 facing the -z direction. Furthermore, the shape of the heat source 2 is not limited to a circular plate shape; for example, it can also be rectangular.

[0180] As the heat source 2, it is assumed that IC (Integrated Semiconductor Device), LSI (Large-Scale Integrated Circuit Device), CPU (Central Processing Unit), LED (Light Emitting Diode), etc. are included. In the heat spreader 1, the central part of the bottom surface on which the heat source 2 is mounted is called the heated part 3 that receives heat from the heat source 2. The heat received from the heat source 2 in the heated part 3 is transferred to the entire heat spreader 1 and dissipated.

[0181] like Figure 1A As shown, a depressurized, sealed space (internal space) 20 is provided within the shell 50 of the heat spreader 1. Refrigerant CO is sealed within the internal space 20. Using heat received from the heated portion 3, the liquefied refrigerant CO vaporizes and diffuses throughout the internal space 20. The diffused refrigerant CO transfers heat to the outer surface of the heat spreader 1 and then condenses, becoming liquefied refrigerant CO again, which returns to the heated portion 3 via capillary force. The heat transferred to the outer surface of the heat spreader 1 is dissipated to the outside. Thus, through the circulation of refrigerant CO within the internal space 20, heat diffusion occurs throughout the heat spreader 1.

[0182] like Figure 2A and Figure 2BAs shown, the heat spreader 1 includes a lower component 10, an upper component 11, and an intermediate component 12. The lower component 10 is a circular plate-shaped component. The lower surface (-z-plane) of the lower component 10 forms the lower surface of the housing 50 of the heat spreader 1. A heating portion 3 is provided on the lower surface of the lower component 10.

[0183] like Figure 3A and Figure 3C As shown, the lower component 10 has a frame-shaped outer edge portion 10a along its outer edge and an inner region 10b inside the outer edge portion 10a on its upper surface (+z side). The outer edge portion 10a has a joining protrusion that protrudes upwards (+z side) from the inner region 10b. The lower component 10 diffusely joins with the outer edge of the lower surface of the intermediate component 12 at this outer edge portion 10a.

[0184] The internal region 10b of the lower component 10 forms the bottom surface of the internal space 20. For example... Figure 3B As shown, multiple recesses 10c are formed in the internal region 10b. These recesses 10c are rectangular protrusions with four sides arranged along the x and y axes when viewed from the z-axis direction. The recesses 10c are arranged two-dimensionally at predetermined intervals in the x and y axes. Grooves 10d extending along the x and y axes are formed between the recesses 10c. These grooves 10d serve as capillary flow paths 4 for the liquefied refrigerant CO to pass through (see Figure 5).

[0185] like Figure 3A , Figure 3C as well as Figure 3B As shown, a plurality of cylindrical engagement protrusions 40 are formed along the surface direction in the inner region 10b of the lower component 10.

[0186] The upper component 11 is a rectangular flat plate, and its shape and size are similar to... Figure 2A and Figure 2B The upper component 11 is identical to the lower component 10 shown. The lower surface (the surface on the -z side) of the upper component 11 forms the top surface of the internal space 20 of the heat spreader 1. An outer edge 10a and an inner region 10b are also provided on the lower surface (the -z surface) of the upper component 11. In the inner region 10b, recesses 10c are formed in a two-dimensional arrangement at predetermined intervals in the x-axis and y-axis directions, and two-dimensional grid-like grooves 10d extending along the x-axis and y-axis directions. Furthermore, in the inner region 10b of the upper component 11, a plurality of cylindrical engagement protrusions 40 are also formed at positions opposite to the engagement protrusions 40 of the lower component 10.

[0187] like Figure 4A and Figure 4CAs shown, the intermediate component 12 has a rectangular frame-shaped outer edge portion 12a along its outer edge and an inner region 12b inside the outer edge portion 10a. The outer edge portion 12a diffusely joins with the outer edge portion 10a of the lower component 10 on its lower surface side and diffusely joins with the outer edge portion 10a of the upper component 11 on its upper surface side.

[0188] like Figure 4A and Figure 4C As shown, the internal region 12b is divided into a capillary flow path forming region 15 and a vapor flow path forming region 16. The capillary flow path forming region 15 is located at the center of the internal region 12b, and extends radially from its center towards the periphery of the internal region 12b, i.e., the outer edge 12a. The vapor flow path forming regions 16 are arranged between the radially extending capillary flow path forming regions 15. The capillary flow path forming regions 15 and the vapor flow path forming regions 16 are arranged alternately along the circumferential direction of a circle centered on the center of the internal region 12b.

[0189] Engaging protrusions 17 are formed between the capillary flow path forming region 15 and the vapor flow path forming region 16, and within the capillary flow path forming region 15, to engage with the lower component 10 and the upper component 11. These engagement protrusions 17 enable the heat spreader 1 to resist increases in internal pressure caused by increases in internal temperature due to heating from the heat source 2 and an increase in ambient temperature, or to resist increases in external pressure caused by external forces. Furthermore, these engagement protrusions 17 separate the capillary flow path forming region 15 from the vapor flow path forming region 16.

[0190] like Figure 4B As shown, in the capillary flow path forming region 15, a plurality of rectangular through holes 12c constituting the capillary flow path are arranged in two dimensions at a predetermined interval in the x-axis and y-axis directions. Figure 4A and Figure 4C As shown, in the vapor flow path forming region 16, the plate is hollowed out, forming a gap larger than that in the capillary flow path forming region 15.

[0191] In addition, such as Figure 4A and Figure 4C As shown, a plurality of cylindrical engagement protrusions 41 are formed along the surface direction in the capillary flow path forming region 15. The engagement protrusions 41 are formed at positions that abut against the engagement protrusions 40 of the lower component 10 and the upper component 11. Furthermore, in the lower component 10 and the upper component 11, the engagement protrusions 40 provided at positions corresponding to the vapor flow path forming region 16 of the intermediate component 12 are formed to be higher than the engagement protrusions 40 provided at positions corresponding to the capillary flow path forming region 15.

[0192] Back Figure 2A and Figure 2BAlong the z-axis, the lower component 10, the middle component 12, and the upper component 11 are sequentially joined, as shown below. Figure 5A and Figure 5B As shown, a housing 50 for the heat spreader 1 is formed. In this case, in the capillary flow path forming region 15 of the intermediate component 12, the joining protrusion 40 of the lower component 10 and the joining protrusion 41 of the intermediate component 12 are diffusely joined by pressure, and the joining protrusion 40 of the lower component 10 and the joining protrusion 41 of the intermediate component 12 are diffusely joined by pressure, thus forming a spacer 42. At this time, the spacer 42 is formed between the lower component 10 and the intermediate component 12, and between the upper component 11 and the intermediate component 12, in a gapless state. In addition, in the vapor flow path forming region 16 of the intermediate component 12, the joining protrusion 40 of the lower component 10 and the joining protrusion 40 of the upper component 11 are diffusely joined, thus forming a spacer 42. The spacer 42 is formed to strengthen the housing 50 in the thickness direction to prevent the internal space 20 from being crushed or expanded, and a plurality of them are formed in the surface direction of the housing 50. In this embodiment, the spacer 42 and the joining protrusion 17 correspond to the reinforcing members.

[0193] [Reinforced Components]

[0194] Here, we consider the case where a vapor chamber 1 is used as a mounting substrate for electronic components. In order to achieve appropriate thermal conductivity in the vapor chamber 1, the value of the Biot number, as defined by the following formula, needs to be set appropriately.

[0195] [Mathematical Formula 12]

[0196]

[0197] Here, Bi[-] is the Biot number, a dimensionless number representing the ratio of the internal thermal resistance of the casing 50 to the thermal resistance during heat dissipation from the casing 50 to the outside of the system. Additionally, h[W·m] -2 K -1 [L] is the thermal conductivity when heat is dissipated from the housing 50 to the outside of the system. L [m] is a representative length related to the size of the housing 50, k [W·m]. -1 ・K -1 [ ] is the thermal conductivity of the housing 50. Furthermore, when the heat conduction path from the housing 50 to the outside of the system consists of multiple components, the overall thermal conductivity can be appropriately used as the thermal conductivity.

[0198] If the Biot number Bi[-] is large, the in-plane temperature non-uniformity of the shell 50 will increase; conversely, if the Biot number Bi[-] is small, the temperature non-uniformity of the shell 50 will decrease. If the in-plane temperature non-uniformity of the shell 50 is large, the thermal stress generated in the plane will become uneven. The unevenness of the in-plane thermal stress is caused by the uneven deformation due to thermal expansion within the plane of the shell 50.

[0199] If the deformation within the surface of the housing 50 becomes uneven, the distribution of external forces such as shear stress and tensile stress acting on the wiring pattern will also become uneven. If these stresses repeatedly and continuously act with the increase or decrease of heat generation, they may damage the circuit components. Therefore, it is necessary to suppress the temperature unevenness within the surface of the housing 50. In order to suppress the temperature unevenness within the surface of the housing 50 to an appropriate value, it is necessary to reduce the value of the Biot number Bi[-]. According to the above formula (1), in order to reduce the Biot number Bi[-], it is only necessary to reduce the thermal conductivity when dissipating heat to the outside of the system, or to shrink the housing 50, or to increase the value of the thermal conductivity of the housing 50.

[0200] The size of the housing 50 is now determined by the mounting area required for the components mounted on the housing 50. The mounting area required for the components mounted on the housing 50 is determined by determining the function of the housing 50 and the constituent components used to achieve that function. That is, it is not possible to reduce the size of the substrate to reduce the Biot number Bi[-] while ensuring the function of the housing 50.

[0201] On the other hand, if the heat generated from the casing 50 is set as Q out [W], then according to Newton's law of cooling, we can obtain the following formula.

[0202] [Mathematical Formula 13]

[0203]

[0204] Here, A s [m] 2 ] is the surface area of ​​the substrate, U s [W·m] -2 ・K -1 [T] is the total thermal conductivity based on the back surface area when heat is dissipated from the side opposite to the component mounting surface of the housing 50 (hereinafter referred to as the back surface of the housing 50) to the outside of the system. s [K] is the back surface temperature, T a [K] is the ambient temperature.

[0205] Here, if the average value of the surface of housing 50 is < U s > to serve as U s Then equation (2) is transformed into the following form.

[0206] [Mathematical Formula 14]

[0207]

[0208] Therefore, the following formula can be derived.

[0209] [Mathematical Formula 15]

[0210]

[0211] Here, <T s > [K] is the average temperature on the back side.

[0212] Here, Q out The efficiency of the electrical power supplied to the components mounted on the housing 50 and their operation is determined by the amount of electricity supplied. Therefore, during the period when the housing 50 performs the desired operation, if the overall thermal conductivity h [W·m] is reduced in order to reduce the Biot number Bi [-], the efficiency of the operation will be affected. -2 K -1 If the temperature of the back surface of the housing 50 increases, the temperature of the components installed at that location will also increase, leading to reduced operating efficiency and shorter lifespan. Therefore, reducing the overall thermal conductivity h to decrease the Biot number Bi[-] is not appropriate. In other words, increasing the thermal conductivity of the device is the only option to reduce the in-plane temperature unevenness of the housing 50 while the device of a specified size is performing its specified function.

[0213] The vapor chamber 1 described in this embodiment is a heat diffusion plate with a higher thermal conductivity than a copper plate. The vapor chamber 1 possesses heat resistance for high-temperature processes such as surface mounting of electronic components based on reflow soldering, and can suppress in-plane temperature unevenness of the housing 50, which can cause reliability issues during electronic component mounting. Furthermore, the vapor chamber 1 can suppress changes in thermal performance caused by its installation posture, and can suppress the generation of uneven temperature distribution of the refrigerant CO.

[0214] The heat spreader 1 described in this embodiment has heat resistance for high-temperature processes such as surface mounting. Specifically, in the heat spreader 1, the bending deformation δ of the housing 50... max [mm] is designed to satisfy the following relationship.

[0215] [Mathematical Expression 16]

[0216]

[0217] Here, δ c [mm] is the allowable amount of bending deformation on the surface of the heat spreader 1.

[0218] Inside the heat spreader 1, a spacer 42 is provided to suppress deformation caused by internal pressure or external force. Here, let L be the value of the largest portion of the spacing between adjacent spacers 42 inside the heat spreader 1. sp．max [mm], then δ max It is given by the following formula.

[0219] [Mathematical Expression 17]

[0220]

[0221] Here, w [N / mm] is the uniformly distributed load caused by an increase in internal or external pressure. Additionally, E [N / mm] 2 [I] is the longitudinal elastic modulus of the component forming the housing 50 of the heat spreader 1. Additionally, I [mm] 4 [ ] is the moment of inertia of the cross section of shell 50.

[0222] Under rising internal pressure, the value of the uniformly distributed load w [N / mm] is based on the internal temperature T of the heat exchanger 1 in the high-temperature process. vc The saturated vapor pressure P of the refrigerant in [K] s．vc [Pa] is used for calculation. Furthermore, P... s．vc [Pa] can be calculated, for example, using Antoine's formula for refrigerants. Additionally, if the refrigerant CO is a mixture, it can be calculated, for example, using Wilson's formula. Furthermore, various external forces are assumed to cause the increase in external pressure, but for example, the uniformly distributed load w [N / mm] can be estimated based on the magnitude of the force applied to the heat spreader 1 during the process of forming an electronic component using the heat spreader 1 as a mounting substrate. For example, the uniformly distributed load w [N / mm] can be estimated based on the pressure applied to the heat spreader 1 using a press during the process of bonding the heat spreader 1 to the insulating substrate.

[0223] Thus, in this embodiment, the spacing L between the adjacent spacers 42 and the connecting protrusions 17 in the heat spreader 1 is... sp [mm] is conditional upon satisfying the following formula.

[0224] [Mathematical Formula 18]

[0225]

[0226] Furthermore, the right side of the above equation (6) is set as the maximum interval L. sp．max [mm]. For example Figure 5A and Figure 5B As shown, the protrusions 17 used for engagement are L apart. sp．max The portion above [mm] is provided with an isolation element 42, thereby satisfying the above formula (6) in the heat spreader 1.

[0227] According to the above equation (6), L sp The smaller the value of [mm], the smaller the maximum deformation. However, since the separator 42 is a portion joined in the thickness direction, refrigerant CO cannot flow in that portion. Therefore, in the heat spreader 1 according to this embodiment, the capillary flow path 4 is designed to satisfy conditions 1 to 4 for achieving an appropriate amount of refrigerant circulation.

[0228] An internal space 20 is formed within the housing 50, and a heated portion 3 is provided at the portion that engages with the heat source 2. A capillary flow path 4 and a vapor flow path 5 are formed within this internal space 20, and refrigerant CO is sealed inside. In the unheated state, the refrigerant CO exists in equilibrium, with a portion existing as a liquid in the capillary flow path 4 containing the liquid heated portion 3 and the remainder existing as a gas in the vapor flow path 5, based on the saturated vapor pressure of the refrigerant CO at the temperature where the heat spreader 1 is provided.

[0229] If heated by the heat source 2 in the heated section 3, the refrigerant CO vaporizes. The vapor flow path 5 causes the vaporized refrigerant CO in the heated section 3 to move towards the outer edge when viewed along the z-axis. The transported vaporized refrigerant CO dissipates heat to the shell 50, gradually condenses and liquefies, and enters the capillary flow path 4. The capillary flow path 4 transports the liquefied refrigerant CO to the heated section 3 through capillary force.

[0230] like Figure 6A As shown, the width of the recess 10c in the x-axis direction and the y-axis direction on the inner region 10b of the lower component 10 is set as L. DT [m]. Furthermore, the width of the groove 10d is set to 2W [m]. The groove 10d is arranged with a grid spacing P1 [m] in both the x-axis and y-axis directions. The micro-flow path formed by this groove 10d is the first micro-flow path 31. The first micro-flow path 31 is a two-dimensional grid-like flow path formed along the surface direction of the heat exchange plate 1 with a uniform grid spacing P1.

[0231] like Figure 6B As shown, the width of the through hole 12c in the x-axis and y-axis directions of the intermediate component 12 is 2W, and they are arranged at a spacing of P2 [m] in the x-axis and y-axis directions. The through hole 12c is located at the grid points where the lines intersect in the x-axis and y-axis directions of the groove 10d of the lower component 10 and the upper component 11. Figure 6B In this embodiment, the arrangement spacing P2 of the through hole 12c in the x-axis and y-axis directions is twice the grid spacing P1 of the grid points in the groove 10d, but it is not limited to this. In this embodiment, the grid spacing P1 and the arrangement spacing P2 can be adjusted by the design method involved in this embodiment.

[0232] like Figure 6C As shown, the height of recess 10c is 2H. Additionally, the depth of the through hole 12c is L. DTThe depth of the through hole 12c is the same as the thickness of the intermediate component 12 and can be changed to any value. The grooves 10d of the lower component 10 and the upper component 11 communicate with the through hole 12c of the intermediate component 12, thus forming a micro-flow path that extends along the thickness direction of the heat exchange plate 1 and is arranged in two dimensions along the surface direction of the heat exchange plate 1, i.e., the x-axis direction and the y-axis direction, at an arrangement spacing P2. This micro-flow path is the second micro-flow path 32. That is, the capillary flow path 4 has the second micro-flow path 32.

[0233] like Figure 7A As shown, the first micro-flow path 31 includes a straight pipe section 31A and a connecting section 31B. The straight pipe section 31A is a tubular portion that extends along the x-axis or y-axis and unidirectionally transports a fluid block (hereinafter referred to as fluid block CA) of refrigerant CO. The straight pipe section 31A has four inner wall surfaces with a rectangular cross-section orthogonal to the flow direction of the liquefied refrigerant CO fluid block (hereinafter referred to as fluid block CA), through which capillary force is generated. The connecting section 31B is disposed at the grid points of the first micro-flow path 31, connecting the straight pipe sections 31A to each other at the grid points. The first micro-flow path 31 is constructed by alternately arranging the straight pipe sections 31A and the connecting sections 31B along the x-axis and y-axis directions.

[0234] like Figure 7B As shown, the second micro-flow path 32 is arranged at a spacing P2 and is connected to the connecting portion 31B of the first micro-flow path 31. Figure 7B As shown, the connecting portion 31B includes: a first connecting portion 31B-1 not connected to the second micro-flow path 32, and a second connecting portion 31B-2 connected to the second micro-flow path 32. In this embodiment, the arrangement spacing P2 of the second micro-flow path 32 is twice the grid spacing P1 of the connecting portion 31B, so one of every two consecutive connecting portions becomes the second connecting portion 31B-2.

[0235] In the design method of this embodiment, a capillary flow path 4 having a heat spreader 1 with the structure described above is designed. In this design method, a first condition, a second condition, a third condition, and a fourth condition are specified as conditions that the capillary flow path 4 should satisfy. The first condition is the capillary force f applied to the fluid block CA in the straight tube section 31A. c [N] The acceleration a generated by the fluid block CA is positive (refer to...). Figure 8A and Figure 8B The second condition is achieved by applying a capillary force f to the fluid block CA in the connecting part 31B. c [N] while the acceleration a generated by the fluid block CA gap a gap．btmThe third condition is that the sum of the work done by the force applied to the fluid block CA in the straight pipe section 31A in the first micro-flow path 31 and the work done by the force applied to the fluid block CA in the connecting section 31B is positive (see reference). Figure 9 The fourth condition is that the total latent heat of vaporization per unit time of the fluid block CA returning from the capillary flow path 4 to the heating section 3 exceeds the amount of heat input per unit time from the heat source 2 to the heating section 3 (refer to...). Figure 10A and Figure 10B The first to fourth conditions will be explained in detail below.

[0236] [First condition]

[0237] The first condition is achieved by applying a capillary force f to the fluid block CA in the straight tube section 31A. c [N] The acceleration a generated by the fluid block CA is positive. For example... Figure 8A and Figure 8B As shown, in the capillary flow path 4, if the capillary force generated in the straight tube section 31A is set as f... c [N], let F be the resistance that hinders the movement of the fluid block CA based on capillary force fc[N]. R [N], then the following formula must be satisfied.

[0238] [Mathematical Formula 19]

[0239]

[0240] For example, in the first micro-flow path 31, for example, Figure 8A and Figure 8B The density of the continuously moving fluid block CA shown is set as ρ [kg / m³]. 3 Let the volume of fluid block CA be V [m]. 3 Furthermore, the capillary force f passing through the straight tube section 31A... c [N] And the acceleration generated by the fluid block CA is set as a [m / s²] 2 When the fluid block CA as a whole satisfies the first condition, the equation of motion is given by the following formula.

[0241] [Mathematical Formula 20]

[0242]

[0243] Based on equations (7) and (8) above, the following equations can be obtained.

[0244] [Mathematical Formula 21]

[0245]

[0246] The first micro-flow path 31, extending along the surface direction of the heat spreader 1, is characterized in that the fluid block CA moving inside it satisfies equation (9). Equation (9) is a conditional expression representing a first condition. By satisfying this conditional expression, the fluid block CA is able to move within the straight pipe section 31A.

[0247] In addition, resistance F R [N] represents the various resistances f acting on the refrigerant CO. Ri The sum of [N] is given by the following formula.

[0248] [Mathematical Expression 22]

[0249]

[0250] N is a positive integer representing the assumed resistance F. R The number of types of [N]. As resistance F R [N] includes the viscous force f generated by the inner wall surface of the flow path. R1 [N]. Additionally, when the refrigerant CO moves vertically upwards on Earth, gravity f... R2 [N] is also included in the resistance F R [N]. Furthermore, when the heat exchanger 1 undergoes accelerated motion, the inertial force f generated by this accelerated motion... R3 [N] is also included in the resistance F R [N]. When the refrigerant CO is an electromagnetic fluid and the heat exchanger 1 is placed in a magnetic field, the electromagnetic force (Lorentz force) generated in the electromagnetic fluid is also included in the resistance F. R [N]. That is, the resistance F that hinders the movement of the fluid block CA based on capillary force. R [N] includes viscous force f R1 Gravity f R2 [N], inertial force f R3 [N] and at least one of the electromagnetic forces.

[0251] [Capillary force f] c ]

[0252] like Figure 8A and Figure 8B As shown, when the cross-section of the straight pipe section 31A, orthogonal to the flow direction of the fluid block CA, is rectangular, and the distance between the inner wall surfaces of the straight pipe section 31A opposite to the thickness direction is set to 2H [m], the distance between the inner wall surfaces of the straight pipe section 31A opposite to the surface direction of the heat exchange plate 1 is set to 2W [m], the surface tension of the fluid block CA relative to the inner wall surface is set to σ [N / m], and the contact angle between the fluid block CA and the inner wall surface is set to θ [rad], the capillary force f c [N] is defined by the following formula.

[0253] [Mathematical Formula 23]

[0254]

[0255] [Viscous force f] R1 ]

[0256] On the other hand, f R1 [N] is defined as the viscous force generated by the shear stress experienced from the inner wall surface due to the movement of the fluid block CA. In this case, the length of the fluid block CA in the direction in which the first micro-flow path 31 extends is defined as h [m], and the length of the straight pipe portion 31A in the direction in which the fluid block CAg flows is defined as L. DT The spacing of the straight pipe sections 31A in the direction of fluid block CA flow is set to L. DP The inner wall surface along the thickness direction of the heat spreader 1 (refer to...) Figure 8A Let the shear stress generated be τ. w．sp [Pa] will be on the inner wall surface along the direction of the heat spreader 1 (refer to...) Figure 8B Let the shear stress generated be τ. w．dp [Pa]. Furthermore, the ratio of the number of first connection portions 31B-1 not connected to the second micro-flow path 32 to the number of connection portions 31B containing fluid block CA is set as ε. ε is 0 when all connection portions 31B are connected to the second micro-flow path, and 1 when all connection portions 31B are not connected to the second micro-flow path.

[0257] If the viscous force generated by the fluid block CA as a whole is set as f R1 [N], then f R1 [N] is represented by the following formula.

[0258] [Mathematical Formula 24]

[0259]

[0260] Furthermore, h can be set to any value, but in the worst case, it can be set to the maximum length from the heated part 3 to the outside of the internal space 20.

[0261] Assume that the resistance F experienced by the fluid block CA R [N] is only the viscous force f R1 [N], then the first condition that the first micro-flow path 31 should satisfy, equation (9), is transformed into the following form.

[0262] [Mathematical Formula 25]

[0263]

[0264] [Gravity f] R2 ]

[0265] Furthermore, when the fluid block CA moves in a non-horizontal direction on Earth, the gravitational force f... R2 [N] The motion of fluid block CA is affected by the elevation angle of its moving direction. Wherein, gravity f R2 [N] becomes the direction that resists the movement of fluid block CA, and its greatest influence is when fluid block CA moves vertically upward. In this case, the condition that the first micro-flow path 31 should satisfy in order to make fluid block CA move vertically upward and realize the circulation of refrigerant CO is expressed by the following formula.

[0266] [Mathematical Formula 26]

[0267]

[0268] Suppose that the device equipped with the heat spreader 1 is accelerating at a speed of a. vc [m / s] 2 Under motion, the resistance F applied to the fluid block CA R [N] needs to include inertial force f R3 [N]. Inertial force f R3 [N] reaches its maximum when the direction of movement of the fluid block CA is the same as the direction of acceleration of the entire heat exchanger 1. Therefore, when gravity f is generated... R2 [N] and inertial force f R3 In the case of [N], the first condition that the first micro-flow path 31 should satisfy in order to realize the circulation of refrigerant CO is the following formula.

[0269] [Mathematical Expression 27]

[0270]

[0271] Similarly, an electromagnetic force f can be added to the above formula. R4 [N] as resistance F R [N].

[0272] [Second Condition]

[0273] The second condition is the capillary force f applied to the fluid block CA in the connecting part 31B. c．gap [N] The viscous force f that exceeds the resistance to the movement of the fluid block CA R1 [N], gravity f R2 [N], inertial force f R3 [N] and electromagnetic force f R4 At least one of the resistance F of [N] R .exist Figure 8A and Figure 8BIn the fluid block CA shown, capillary force is generated not only in the straight pipe section 31A but also in the connecting section 31B. As described above, the connecting section 31B contains a first connecting section 31B-1 that is not connected to the second micro-flow path 32, and a second connecting section 31B-2 that is connected to the second micro-flow path 32. In the connecting section 31B, there are no inner wall surfaces on either side in the planar direction, but in the first connecting section 31B-1 that is not connected to the second micro-flow path 32, there is an inner wall surface in the thickness direction. Let the capillary force in this case be f. c．gap When [N], f c．gap [N] is shown below.

[0274] [Mathematical Formula 28]

[0275]

[0276] Assume that the fluid block CA is moving horizontally. If the capillary force f passing through the first connection 31B-1... c．gap [N] Let the acceleration generated by the fluid block CA be a gap [m / s] 2 The second condition that should be satisfied in the first connection part 31B-1 that is not connected to the second micro-flow path 32 is expressed by the following formula.

[0277] [Mathematical Formula 29]

[0278]

[0279] If we take gravity f into account R2 [N], then the conditions that should be satisfied in the first connecting part 31B-1 are transformed into the following formula.

[0280] [Mathematical Formula 30]

[0281]

[0282] If we take into account the inertial force f R3 [N], then equation (3) is transformed into the following equation.

[0283] [Mathematical Formula 31]

[0284]

[0285] Similarly, an electromagnetic force f can be added to the above formula. R4 [N] acts as resistance.

[0286] Furthermore, the capillary force generated in the second connection portion 31B-2, which is connected to the second micro-flow path 32, is set to f. c．gap.btm When [N], f c．gap.btm [N] is shown below.

[0287] [Mathematical Formula 32]

[0288]

[0289] Assume that the fluid block CA is moving horizontally. Let a be the acceleration generated in the fluid block CA by the capillary force in the second connection 31B-2. gap．btm [m / s] 2 ], then the conditional expression that should be satisfied as the second condition in the second connecting part 31B-2 is the following expression.

[0290] [Mathematical Formula 33]

[0291]

[0292] If we take gravity f into account R2 [N], then the conditional expression that should be satisfied as the second condition in the second connecting part 31B-2 is in the following form.

[0293] [Mathematical Formula 34]

[0294]

[0295] If we take into account the inertial force f R3 [N], then the conditional expression for the second condition is as follows.

[0296] [Mathematical Formula 35]

[0297]

[0298] Similarly, an electromagnetic force f can be added to the above formula. R4 As a resistance.

[0299] [Third condition]

[0300] The third condition is that the sum of the work applied to the fluid block CA in the straight pipe section 31A and the work applied to the fluid block CA through the connecting section 31B is positive. In order for the heat exchanger 1 to function, the fluid block CA needs to pass through the connecting section 31B without remaining stationary. As long as equations (16) to (19) and equations (20) to (23), i.e. the second condition, are satisfied, the fluid block CA will also move with positive acceleration in the direction of flow in the connecting section 31B, so the fluid block CA can pass through the connecting section 31B.

[0301] However, even if the second condition is not met, when the refrigerant CO reaches the inner wall of the partially continuous straight pipe section 31A again through the connecting section 31B, it can still pass through the connecting section 31B if it has a velocity of 0 or greater in a direction approximately in the same direction as the original direction of refrigerant CO's travel. As a condition for having this velocity, the refrigerant CO can pass through the connecting section 31B when the sum of the work done on the fluid block CA in the straight pipe section 31A and the work done on the fluid block CA in the connecting section 31B is positive, that is, when positive work is done relative to the direction of refrigerant CO's travel. This is the third condition, which is given by the following formula.

[0302] [Mathematical Formula 36]

[0303]

[0304] The above formula represents Figure 9 The work done by the force applied to the fluid block CA from P1 to P2, i.e., in the straight pipe section 31A, is shown in the diagram. The second item on the left represents... Figure 9 The work done by the force applied to the fluid block CA from P2 to P3 (length 2W of the connecting part 31B in the direction of fluid block CA flow) is shown. Equation (24) indicates that the sum of the above work is positive.

[0305] [Fourth condition]

[0306] The fourth condition is the latent heat of vaporization Q per unit time of the fluid block CA returning from the capillary flow path 4 to the heated section 3. LH The total amount of [J / kg] exceeds the amount of heat input Q per unit time from heat source 2 to heat receiving part 3. in [W]. In the heat spreader 1, the latent heat of vaporization Q of the refrigerant CO corresponding to the amount of refrigerant CO that returns to the heat source 2 per unit time during a series of cycles of the refrigerant CO. LH The total amount exceeds the heat input Q generated from heat source 2. in [W], thereby enabling the continuous supply of the amount of refrigerant CO required to maintain continuous evaporation to the heated section 3 located inside the surface in contact with the heat source 2. Conversely, if the amount of refrigerant CO required to maintain continuous evaporation cannot be supplied to the heated section 3, a phenomenon known as "drying out" occurs. If drying out occurs, continuous latent heat transfer based on refrigerant CO cannot be carried out, and the thermal performance of the heat spreader 1 decreases, resulting in an increase in the thermal resistance of the heat spreader 1.

[0307] Here, the amount of heat input per unit time from the heat source 2 in the heated section 3 is set as Q. in [W], let Q be the latent heat of vaporization per unit mass of fluid block CA of refrigerant CO. LH[J / kg]. Additionally, such as... Figure 10A and Figure 10B As shown, the curve constituting the outer edge of the heated section 3 is designated as circle C. The first micro-flow path 31 facing circle C is designated as N. 1．C The i-th (i = 1 to N) 1．C Let the cross-sectional area of ​​the section of the first micro-flow path 31 orthogonal to the flow direction of the fluid block CA be S. A1．i [m] 2 Let v be the velocity of the fluid block CA flowing in the i-th first micro-flow path 31. 1．i [m / s]. Furthermore, the number of second micro-flow paths 32 connected to the heated section 3 is set to N. 2．P , the j-th (j = 1 to N) 2．P Let the cross-sectional area of ​​the section of the second micro-flow path 32 orthogonal to the direction of refrigerant CO flow be S. A2．j [m] 2 Let v be the velocity at which the fluid block CA flows in the j-th second micro-flow path 32 and returns to the heated part 3. 2．j [m / s]. In order for the heat spreader 1 to continue to perform the desired function without drying out, the following relationship needs to be satisfied.

[0308] [Mathematical Formula 37]

[0309]

[0310] In the design method of the heat spreader 1 in this embodiment, the type of refrigerant CO and the material of the heat spreader 1 are selected in such a way that all of the first, second, and fourth conditions are satisfied, or all of the first, third, and fourth conditions are satisfied, and the values ​​of the design parameters related to the flow path structure of the capillary flow path 4 are determined. These design parameters include parameters specifying the length of the capillary flow path 4 and the cross-section orthogonal to the direction of refrigerant CO flow. Therefore, even with viscous force f... R1 [N], gravity f R2 [N] Equal resistance F R Even when acting as a resistance to the flow of refrigerant CO, refrigerant CO circulation can still be achieved. Furthermore, to alleviate the uneven distribution of refrigerant, in a first micro-flow path 31 with a discontinuous structure on at least one side of the inner wall surface, refrigerant CO can pass through the discontinuous parts of the inner wall surface, i.e., the connecting portion 31B, without remaining stationary. Moreover, the heating section 3 can have a micro-flow path structure that allows continuous delivery from the heating section 3 to the condensing section without causing it to dry out.

[0311] The operation of the heat spreader 1 with the above structure will be explained. For example... Figure 4A and Figure 4CAs shown, heat emitted from the heat source 2 is transferred to the heated part 3, and through this heat, the refrigerant CO present in the heated part 3 vaporizes. The vaporized refrigerant CO diffuses throughout the entire internal space 20 through the vapor flow path 5. Moreover, most of the vaporized refrigerant CO reaches the outer edge of the internal space 20, transfers heat to the shell 50, and condenses.

[0312] The refrigerant CO, after condensation in the internal region 10b of the upper component 11, is transported to the capillary flow path 4 through the capillary phenomenon in the groove 10d of the internal region 10b. In the capillary flow path 4, the condensed refrigerant CO returns to the heated part 3 through the capillary phenomenon. Thus, the above-described circulation cycle of refrigerant CO is formed within the internal space 20, thereby achieving the cooling of the heat source 2.

[0313] [Design process of heat spreader]

[0314] like Figure 11A As shown, firstly, in a computer HW having a CPU 60, a memory 61, an external storage device 62, an operation unit 63, a display unit 64, and an internal bus 65, the CPU 60 executes a software program read from the external storage device 62 into the memory 61 according to the operation via the operation unit 63, thereby designing the heat spreader 1. The execution result is displayed, for example, on the display unit 64. The information processing device 100, which executes the program to achieve this function, calculates the maximum spacing L between adjacent reinforcing members. sp．max The processing of [mm] and the determination of whether the first to fourth conditions are met, i.e. Figure 11B The design treatment (design method) of the heat spreader 1 shown.

[0315] like Figure 11B As shown, firstly, the information processing device 100 performs initial settings (step S1). In the initial settings, the size, shape, and calorific value of the heat source 2 are set; the type and amount of refrigerant CO are set; and the overall dimensions of the heat spreader 1, the position and size of the heated portion 3, and the shape and dimensions of the heat spreader 1 excluding the capillary flow path 4 are set. Pure water, an organic solvent, or a mixture thereof are selected as the refrigerant CO; copper or similar materials are used as components capable of forming an airtight structure for the heat spreader 1. Thus, the heat input Q per unit time is determined. in [W], latent heat of vaporization Q per unit mass of fluid block LH [J / kg], density ρ of refrigerant CO [kg / m³] 3 The surface tension σ [N / m] of fluid block CA relative to the inner wall surface, and the contact angle θ [rad] between refrigerant CO and the inner wall surface. Additionally, the length h [m] and volume V [m³] of fluid block CA. 3The value is determined by using the length from the heated part 3 to the outer edge of the internal space 20 instead, but can be set to any value. In this step S1, the material and size of the shell 50 are determined, and therefore the longitudinal elastic modulus E and the moment of inertia I of the section are determined.

[0316] Next, the information processing device 100 calculates the uniformly distributed load w [N / mm]. 2 (Step S10). Here, the internal temperature T of the heat exchanger 1 in the high-temperature process based on the operation of the heat exchanger 1 is... vk The saturated vapor pressure P of refrigerant CO at [K] s．vc [Pa] is used to calculate the uniformly distributed load w [N / mm] caused by the increase in internal pressure. 2 P s．vc [Pa] is calculated using the Antoine formula when the refrigerant CO is a pure substance, and using the Wilson formula when the refrigerant CO is a mixture. Additionally, the uniformly distributed load w [N / mm] caused by external forces is also considered. 2 In the case of […], the calculation is based on the external force expected to be applied to the heat exchanger 1. For example, the external force per unit area involved in the shell 50 can be set as a uniformly distributed load w [N / mm²]. 2 ] .

[0317] Next, the information processing device 100 determines the allowable bending deformation δ of the housing 50. c To calculate the maximum spacing L of adjacent spacers 42 sp．max [mm] (Step S11). Furthermore, in this embodiment, the diameter of the bottom surface of the cylindrical spacer 42 is fixed.

[0318] Next, the information processing device calculates N that satisfies the above equation (25) based on the pre-set size of the heated part 3. 1．C N 2．P S A1．i [m] 2 ], S A2．j [m] 2 ]、v 1．i [m / s], v 2．j [m / s] (step S2). Here, if each S... A1．i [m] 2 Set the value of ] to be the same, and set each S to... A2．j [m] 2 Set the value of ] to be the same, and set v 1．i The value of [m / s], v 2．j If the value of [m / s] is set to be the same, the above value is easy to calculate. This determines the cross-sectional area of ​​the first micro-flow path 31 and the second micro-flow path 32, and the velocity of the fluid block CA. Furthermore, in step S2, for the presence of the maximum interval L set in step S11 above... sp．maxThe calculation assumes that there is no flow path for the isolation element 42 [mm] and the part where the refrigerant CO does not flow.

[0319] Next, the information processing device sets the dimensions of the capillary flow path 4 (step S3). Here, H[m], W[m], and L are set for the first micro-flow path 31. DT [m], L DP The values ​​of the design parameters involved in the construction of the flow paths, such as [m], ε, P1, and P2. The values ​​of these design parameters are influenced by N, which is obtained in step S2. 1．C N 2．P S A1．i [m] 2 ], S A2．j [m] 2 ]、v 1．i [m / s], v 2．j The constraint of [m / s].

[0320] Next, the information processing device uses equations (5), (10), and (14) to calculate the capillary force f. c [N], f c．gap [N], f c．gap．btm [N] (Step S4). Here, the previously determined and set value is used.

[0321] Next, the information processing device calculates the resistance F. R [N] (Step S5). First, using equation (6), the viscous force f is calculated. R1 [N]. τ in equation (6) w．sp [Pa], τ w．dp [Pa] is determined by treating the refrigerant CO as a Newtonian fluid, based on the v obtained in step S2. 1．i The value of [m / s], v 2．j The value of [m / s] is obtained by multiplying the velocity gradient on the wall surface by the viscosity coefficient of the refrigerant CO. Gravity f R2 [N], inertial force f R3 [N], electromagnetic force f R4 [N] is calculated additionally depending on the use of heat spreader 1.

[0322] Next, the information processing device uses equations (3), (11) to (13), and (15) to (17) to calculate the accelerations a and a. gap a gap．btm (Step S6), and use Equation (18) to calculate the total work done (Step S7).

[0323] Next, the information processing device determines whether the calculation results so far satisfy all three conditions (first, second, and fourth) or satisfy all three conditions (step S8). If not, the information processing device returns to step S1 and repeats the processing of steps S1 to S8 until step S8 becomes "yes". During this repetition, the values ​​of the design parameters involved in the flow path construction are changed until the first to fourth conditions are satisfied.

[0324] If the calculation result satisfies all or all of the first, second, and fourth conditions (step S8; yes), the information processing device considers that the values ​​of the design parameters involved in the flow path construction of the capillary flow path 4 have been obtained and ends the design process.

[0325] After this design process, the heat spreader 1 is manufactured based on this design method. In the manufacturing process of the heat spreader 1, if the allowable amount of bending deformation of the shell 50 is set as δ... c [mm], the longitudinal elastic modulus of the shell 50 is set to E [N / mm]. 2 Let the moment of inertia of the cross section of shell 50 be I [mm]. 2 Let w [N / mm] be the load per unit length of the shell 50, i.e., the uniformly distributed load, applied due to the internal or external pressure generated in the internal space 20. Then, the spacing L between the adjacent reinforcing members (spacer 42 and connecting protrusion 17) is... sp [mm] In a manner that satisfies the above formula (6), a reinforcing member (isolation member 42 and joint protrusion 17) is formed in the internal space 20 of the housing 50, thereby manufacturing the heat spreader 1. In addition, in this manufacturing process, the housing 50 with a flow path structure of capillary flow path 4 based on the value of the determined design parameters is formed from the selected material, and the selected refrigerant CO is sealed into the internal space 20 of the housing 50, thereby manufacturing the heat spreader 1.

[0326] The heat spreader 1 manufactured based on this design method has a permissible amount δ for the bending deformation of the shell 50 caused by high heat. c The refrigerant CO, the material of the heat spreader 1, and the flow path structure of the capillary flow path 4 are all within the range that satisfy all or all of the first, second, and fourth conditions. As long as the first to fourth conditions are met, the flow path structure is not limited to... Figures 6A to 9 The construction shown. For example, in Figure 7A and Figure 7B In the connecting part 31B, the first connecting part 31B-1 and the second connecting part 31B-2 are arranged alternately, but if the value of ε is changed, the ratio can be changed.

[0327] [Installation of electronic components]

[0328] like Figure 12 As shown, the heat spreader 1 can be used as a mounting substrate for mounting LED (Light Emitting Diode) elements 70. A thin circuit board 71, serving as an insulating layer, is formed on the upper surface of the heat spreader 1, and the LED elements 70 are densely mounted thereon. The area where the LED elements 70 are mounted becomes the heat-receiving portion 3. Electrodes 72, capable of being electrically connected to an external source, are also provided on the thin circuit board 71 in areas other than the heat-receiving portion 3.

[0329] In fact, a ground layer (not shown) is formed on the thin circuit board 71 to ground the LED element 70. Additionally, as... Figure 13A As shown, a lower surface resist pattern 73 serving as an insulating layer, a wiring pattern 74 serving as a conductive layer, and an upper surface resist pattern 75 serving as an insulating layer are sequentially formed on the ground layer, and an LED element 70 is mounted on it. Figure 13B As shown, the signal electrode 70a of the LED element 70 is soldered to the wiring pattern 74 via an opening in the upper surface resist pattern 75 through a reflow soldering process. The ground electrode 70b of the LED element 70 is soldered to the ground layer via openings in the lower surface resist pattern 73 and the upper surface resist pattern 75 through a reflow soldering process. The heat spreader 1 is designed to withstand the highest temperature in the temperature profile of the reflow soldering process.

[0330] A comparison of the LED junction temperatures was made between the heat spreader 1 and the copper substrate involved in this embodiment. Junction temperature refers to the surface temperature of the LED element 70, which is the operating compensation temperature of the LED element 70. Figure 14 As shown, compared to a copper substrate, the junction temperature can be suppressed by approximately 10K. Furthermore, it is evident that in the heat spreader 1 of this embodiment, the temperature of the mounted LED elements 70 remains almost the same regardless of the location, thus smoothing the temperature distribution.

[0331] [Evaluation Results]

[0332] In fact, the heat spreader 1 manufactured using this design method was evaluated. The heat source 2 is a ceramic heater, and it is cooled by an aluminum radiator 6 mounted on the heat spreader 1. Figure 15A , Figure 15B as well as Figure 15C As shown, the installation angles of the heat spreader 1 were set to 0 degrees, 90 degrees, and 180 degrees, and the thermal resistances for each angle were confirmed. To verify the robustness of the evaluation system, a copper plate (C1020) with the same shape as heat spreader 1 was used as a comparison object. The thermal resistances were calculated using the following formulas, and the results were compared. The evaluation results are as follows: Figure 16 As shown.

[0333] [Mathematical Formula 38]

[0334]

[0335] Here, R th．all [K·W] -1 [ ] is the total thermal resistance of the heat spreader 1 and the copper plate. Additionally, T h [K], T a [K], Q h [W] represents the back temperature of the ceramic heater, room temperature, and the power input to the ceramic heater, respectively.

[0336] like Figure 16 As shown, the difference in thermal resistance of the copper plate due to its mounting posture is approximately 0.5%, which is a value derived from the characteristics of the evaluation system and serves as the benchmark value for evaluating the thermal resistance of the heat spreader 1. The evaluation experiment results show that the difference in thermal resistance of the heat spreader 1 due to its mounting posture is approximately 0.5%, the same as that of the copper plate. No differences exceeding the difference in data derived from the evaluation system were observed; therefore, it can be confirmed that the thermal resistance of the heat spreader 1 designed using the design method described in this embodiment remains constant regardless of the mounting posture.

[0337] Furthermore, even if the power input Q to the ceramic heater h As [W] increases, the total thermal resistance R of the copper plate increases. th．all [K·W] -1 The value remained almost unchanged, but the input power Q to the ceramic heater was confirmed. h The higher [W] becomes, the higher the total thermal resistance R of the heat spreader 1. th．all [K·W] -1 The lower the value, the better. This indicates that the heat diffusion effect of the heat spreader 1 is superior to that of the copper plate.

[0338] Thus, by considering the resistance F of the fluid block CA acting on the refrigerant CO... R And determine the design parameters for a micro-flow path structure that satisfies equation (3), so that the refrigerant CO can resist various resistances F against the refrigerant CO. R [N] moves, realizing the circulation of refrigerant CO. In addition, by appropriately defining the values ​​of geometric parameters such as the volume V of the fluid block CA according to the shape of the flow path, it is possible to obtain the conditional expression that the shape of the capillary flow path 4 should satisfy for a capillary flow path 4 with an arbitrary shape.

[0339] As detailed above, according to the above embodiment, the spacing between adjacent spacers 42 is L. sp The shell 50 is arranged in a manner within [mm] in the internal space 20 to prevent deformation of the shell 50. Therefore, the amount of bending deformation of the shell 50 caused by high temperature can be contained within the allowable amount δ.c Therefore, it can suppress deformation caused by the increase in internal pressure due to high heat or deformation caused by external forces.

[0340] Furthermore, while the isolator 42 and the engagement protrusion 17 function to achieve mechanical strength, it is difficult to establish a micro-flow path for refrigerant CO to return using capillary force at the location where the isolator 42 is provided. Therefore, if the isolator 42 is over-configured, the required refrigerant CO circulation flow rate of the heat spreader 1 may not be achieved. Therefore, according to the heat spreader 1 of this embodiment, in the first micro-flow path 31 of the capillary flow path 4 formed in a two-dimensional grid with uniform grid spacing P1, the capillary force f applied to the fluid block CA of refrigerant CO is... c [N] Exceeds the resistance F that hinders the movement of the fluid block CA R [N], the work done by the force propelling the fluid block CA forward is positive overall. This allows for the selection of the refrigerant CO and the material of the heat spreader 1 in a manner that prevents drying out in the heated section 3, and the determination of the design parameters representing the flow path structure of the capillary flow path 4. Therefore, continuous thermal diffusion can be achieved without the influence of resistance on thermal performance. This enables the realization of desired thermal performance and suppresses deformation caused by internal pressure increases due to high heat or deformation caused by external forces.

[0341] Alternatively, the engagement protrusion 17 may be omitted. In this case, the spacers 42 are arranged, for example, in a two-dimensional grid pattern, requiring the aforementioned maximum spacing L to be ensured. sp．max The conditions (equation (6) above).

[0342] In the above embodiment, the case where the heat spreader 1 is used as a mounting substrate for mounting the LED element 70 has been described. However, it is not limited to this. It can be used as a mounting substrate for mounting other electronic components.

[0343] In the above embodiment, the case where the cross-section of the flow path orthogonal to the direction of flow of the fluid block WA is rectangular has been described, but it is not limited to this. For example, it can also be applied to flow paths with other polygonal cross-sections.

[0344] This invention can be implemented and modified in various ways without departing from the broad spirit and scope of the invention. Furthermore, the above-described embodiments are for illustrative purposes only and do not limit the scope of the invention. That is, the scope of the invention is not limited by the embodiments, but by the claims. Moreover, various modifications implemented within the scope of the claims and their equivalent inventive meaning are considered to be within the scope of the invention.

[0345] Furthermore, this application claims priority based on Japanese Patent Application No. 2023-70713, filed on April 24, 2023, and the entire description, claims, and drawings of Japanese Patent Application No. 2023-70713 are incorporated herein by reference.

[0346] Industrial availability

[0347] This invention can be applied to heat spreaders for cooling or heating heat sources, and is suitable for use as mounting substrates for electronic components.

[0348] Explanation of reference numerals in the attached figures

[0349] 1…heating plate; 2…heat source (cooled body); 3…heated part; 4…capillary flow path; 5…steam flow path; 6…radiator; 10…lower component; 10a…outer edge; 10b…internal region; 10c…recess; 10d…groove; 11…upper component; 12…middle component; 12a…outer edge; 12b…internal region; 12c…through hole; 15…capillary flow path forming region; 16…steam flow path forming region; 17…jointing protrusion; 20…internal space (sealed space); 31…first micro-flow path; 31A…straight pipe section; 31B…connecting part; 31B- 1…First connecting part; 31B-2…Second connecting part; 32…Second micro-flow path; 40, 41…Connecting protrusions; 42…Isolator; 50…Housing; 60…CPU; 61…Memory; 62…External storage device; 63…Operating unit; 64…Display unit; 65…Internal bus; 70…LED element; 70a…Signal electrode; 70b…Ground electrode; 71…Thin circuit board; 72…Electrode; 73…Resist pattern on lower surface; 74…Wiring pattern; 75…Resist pattern on upper surface; 100…Information processing device; CO…Refrigerant; CA…Fluid block.

Claims

1. A method for designing a heat spreader, executed by an information processing device, wherein, The heat spreader has a flat shell with an internal space. The shell has the following: The heated part receives heat from the cooled part; A vapor flow path for the refrigerant that has vaporized in the heated section; as well as The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the heated section via capillary force. Multiple reinforcing members that strengthen the shell in the thickness direction are arranged along the surface direction of the shell in the internal space. If the allowable amount of bending deformation of the shell is set as δ c [mm], the longitudinal elastic modulus of the shell is set to E [N / mm]. 2 Let the moment of inertia of the shell section be I [mm]. 2 Let w [N / mm] be the load per unit length of the shell caused by the internal or external pressure generated in the internal space, i.e., the uniformly distributed load. Then, let L be the spacing between adjacent reinforcing members. sp [mm] is defined as satisfying the following formula: [Mathematical Formula 1] 。 2. The design method of the heat spreader according to claim 1, wherein, The capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchange plate with a uniform grid spacing. The first micro-flow path has: A straight pipe section, which unidirectionally transports the fluid block of the refrigerant; and The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path. The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight tube section is positive. The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the connecting part is positive. The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive. The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated section from the capillary flow path per unit time exceeds the heat input from the cooled body to the heated section per unit time. The refrigerant and the material of the heat spreader are selected by satisfying all of the first, second, and fourth conditions, or by satisfying all of the first, third, and fourth conditions, and the values ​​of the design parameters involved in the flow path structure of the capillary flow path are determined.

3. A method for designing a heat spreader, executed by an information processing device, wherein, The heat spreader has a flat shell with an internal space. The shell has the following: The heated part receives heat from the cooled part; A vapor flow path for the refrigerant that has vaporized in the heated section; and The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the heated section via capillary force. The capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchange plate with a uniform grid spacing. The first micro-flow path has: A straight pipe section, which unidirectionally transports the fluid block of the refrigerant; and The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path. The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight tube section is positive. The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the connecting part is positive. The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive. The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated section from the capillary flow path per unit time exceeds the heat input from the cooled body to the heated section per unit time. The refrigerant and the material of the housing are selected in such a way that all of the first, second, and fourth conditions are satisfied, or all of the first, third, and fourth conditions are satisfied, and the values ​​of the design parameters involved in the flow path construction of the capillary flow path are determined.

4. The design method of the heat spreader according to claim 3, wherein, Let a [m / s] be the acceleration generated in the fluid block by the capillary force passing through the straight tube section. 2 The density of the fluid block is set as ρ [kg / m³]. 3 Let the volume of the fluid block be V [m]. 3 The capillary force in the straight tube section is set as f. c [N], let F be the resistance that hinders the movement of the fluid block based on the capillary force. R When [N], the following expression shall be used as the conditional expression representing the first condition: [Mathematical Formula 2] ， The capillary flow path includes a second micro-flow path extending along the thickness direction of the housing and arranged in two dimensions with uniform spacing in the surface direction of the housing. The connecting part includes: The first connection portion not connected to the second micro-flow path, and The second connection portion connected to the second micro-flow path, Let a be the acceleration generated in the fluid block by the capillary force in the first connecting part. gap [m / s] 2 Let a be the acceleration generated in the fluid block by the capillary force in the second connecting part. gap．btm [m / s] 2 Let f be the capillary force generated in the first connecting part. c．gap [N], let the capillary force generated in the second connecting part be f. c．gap．btm When [N], the following expression is used as the conditional expression for the second condition: [Mathematical Formula 3] ， The length of the straight pipe section in the direction of fluid block flow is defined as L. DT [m], when the length of the connecting portion in the direction of fluid block flow is set to 2W[m], and the ratio of the number of the first connecting portions to the number of connecting portions where the fluid block exists is set to ε, the following formula is used as the conditional expression for the third condition: [Mathematical Formula 4] ， Let Q be the amount of heat input per unit time from the cooled body in the heated section. in [W], where the latent heat of vaporization per unit mass of the fluid block is set as Q. LH [J / kg], where N is the number of the first micro-flow paths that connect to the outer edge of the heated part. 1．C The number of the second micro-flow paths connected to the heated part is set to N. 2．P Let S be the cross-sectional area of ​​the i-th first micro-flow path that is connected to the outer edge of the heated part and is orthogonal to the direction of fluid block flow. A1．i [m] 2 Let S be the cross-sectional area of ​​the section of the j-th second micro-flow path that is connected to the heated part and is orthogonal to the direction of fluid block flow. A2．j [m] 2 The velocity of the fluid block flowing in the i-th first micro-flow path that is in contact with the outer edge of the heated part is set as v. 1．i [m / s], where v is the velocity of the fluid block flowing in the j-th second micro-flow path connected to the heated part. 2．j When [m / s], the following expression is used as the conditional expression for the fourth condition: [Mathematical Formula 5] ， Where i is 1 to N 1．C A natural number, j is 1 to N 2．P The natural number.

5. The design method of the heat spreader according to claim 4, wherein, The cross-section of the straight pipe section, orthogonal to the direction of fluid block flow, is rectangular. When the distance between the inner wall surfaces facing each other in the thickness direction of the straight pipe section is set to 2H [m], the distance between the inner wall surfaces facing each other in the surface direction of the straight pipe section is set to 2W [m], the surface tension of the fluid block relative to the inner wall surface is set to σ [N / m], and the contact angle between the fluid block and the inner wall surface is set to θ [rad], The capillary force f generated in the fluid block in the straight tube section c [N] is defined by the following formula: [Mathematical Formula 6] ， The capillary force f generated in the fluid block in the first connecting part c．gap [N] is defined by the following formula: [Mathematical Expression 7] ， The capillary force f generated in the fluid block in the second connecting part c．gap．btm [N] is defined by the following formula: [Mathematical Formula 8] 。 6. The design method of the heat spreader according to claim 5, wherein, Let the length of the fluid block in the direction of fluid block flow be h [m], and let the spacing of the straight pipe sections in the direction of fluid block flow be L. DP [m], where the shear stress generated on the inner wall surface along the thickness direction in the first micro-flow path is τ. w．sp [Pa], where the shear stress generated on the inner wall surface along the surface direction in the first micro-flow path is defined as τ. w．dp When [Pa], The resistance F R The viscous force f generated by the fluid mass flowing in the first micro-flow path R1 [N] is defined by the following formula: [Mathematical Expression 9] 。 7. The design method of the heat spreader according to claim 3, wherein, The resistance that prevents the movement of the fluid block based on the capillary force includes at least one of gravity, inertial force, and electromagnetic force.

8. A method for manufacturing a heat spreader, wherein, The heat spreader has a flat shell with an internal space. The shell has the following: The heated part receives heat from the cooled part: A vapor flow path for the refrigerant that has vaporized in the heated section; and The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the heated section via capillary force. Multiple reinforcing members that strengthen the shell in the thickness direction are arranged along the surface direction of the shell in the internal space. If the allowable amount of bending deformation of the shell is set as δ c [mm], the longitudinal elastic modulus of the shell is set to E [N / mm]. 2 Let the moment of inertia of the shell section be I [mm]. 2 Let w [N / mm] be the load per unit length of the shell applied by the internal or external pressure generated in the internal space, i.e., the uniformly distributed load. Then, the spacing L between the adjacent reinforcing members is... sp [mm] The reinforcing member is formed in the internal space of the housing in a manner that satisfies the following formula. [Mathematical Formula 10] 。 9. The method for manufacturing a heat spreader according to claim 8, wherein, The capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchange plate with a uniform grid spacing. The first micro-flow path has: A straight pipe section, which unidirectionally transports the fluid block of the refrigerant; and The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path. The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block through the straight tube is positive. The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the connecting part is positive. The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive. The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated section from the capillary flow path per unit time exceeds the heat input from the cooled body to the heated section per unit time. The refrigerant and the material of the housing are selected by satisfying all of the first, second, and fourth conditions, or by satisfying all of the first, third, and fourth conditions, and the values ​​of the design parameters involved in the flow path construction of the capillary flow path are determined. The housing is formed from the selected material, having a flow path structure of capillary flow path based on the determined design parameters. The selected refrigerant is sealed into the internal space of the housing.

10. A method for manufacturing a heat spreader, wherein, The heat spreader has a flat shell with an internal space. The shell has the following: The heated part receives heat from the cooled part; A vapor flow path for the refrigerant that has vaporized in the heated section; and The capillary flow path transports the refrigerant, which has liquefied due to heat dissipation, to the heated section via capillary force. The capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchange plate with a uniform grid spacing. The first micro-flow path has: A straight pipe section, which unidirectionally transports the fluid block of the refrigerant; and The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path. The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block through the straight tube is positive. The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the connecting part is positive. The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive. The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated section from the capillary flow path per unit time exceeds the heat input from the cooled body to the heated section per unit time. The refrigerant and the material of the housing are selected by satisfying all of the first, second, and fourth conditions, or by satisfying all of the first, third, and fourth conditions, and the values ​​of the design parameters involved in the flow path construction of the capillary flow path are determined. The housing is formed from the selected material, having a flow path structure of capillary flow path based on the determined design parameters. The selected refrigerant is sealed into the internal space of the housing.

11. A heat spreader having a flat, plate-shaped shell with an internal space, wherein the shell includes: a heating portion for receiving heat from a cooled body; a vapor flow path for moving refrigerant vaporized in the heating portion; and a capillary flow path for capillary force conveying refrigerant liquefied due to heat dissipation to the heating portion, wherein a plurality of reinforcing members reinforcing the shell in the thickness direction are arranged along the surface direction of the shell in the internal space, wherein... If the allowable amount of bending deformation of the shell is set as δ c [mm], the longitudinal elastic modulus of the shell is set to E [N / mm]. 2 Let the moment of inertia of the shell section be I [mm]. 2 Let w [N / mm] be the load per unit length of the shell caused by the internal or external pressure generated in the internal space, i.e., the uniformly distributed load. Then, let L be the spacing between adjacent reinforcing members. sp [mm] is defined as satisfying the following formula: [Mathematical Formula 11] 。 12. The heat spreader according to claim 11, wherein, The capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchange plate with a uniform grid spacing. The first micro-flow path has: A straight pipe section, for unidirectionally conveying the fluid block of the refrigerant; and The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path. The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight tube section is positive. The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the connecting part is positive. The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive. The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated section from the capillary flow path per unit time exceeds the heat input from the cooled body to the heated section per unit time. The refrigerant, the material of the heat spreader, and the flow path structure of the capillary flow path are all satisfied, including the first condition, the second condition, and the fourth condition, or the first condition, the third condition, and the fourth condition.

13. A heat spreader, which is flat and has a flat shell with an internal space, wherein the shell has: a heating section for receiving heat from a cooled body; a vapor flow path for moving refrigerant vaporized in the heating section; and a capillary flow path for capillary force conveying refrigerant liquefied due to heat dissipation to the heating section, wherein... The capillary flow path comprises a two-dimensional grid-like flow path, i.e., a first micro-flow path, formed along the surface direction of the heat exchange plate with a uniform grid spacing. The first micro-flow path has: A straight pipe section, which unidirectionally transports the fluid block of the refrigerant; and The connecting portion connects the straight pipe sections to each other at the grid points of the first micro-flow path. The first condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the straight tube section is positive. The second condition is that the acceleration generated in the fluid block by the capillary force applied to the fluid block in the connecting part is positive. The third condition is that the sum of the work done by the force applied to the fluid block in the straight pipe section and the work done by the force applied to the fluid block in the connecting section is positive. The fourth condition is that the total latent heat of vaporization of the fluid block returning to the heated section from the capillary flow path per unit time exceeds the heat input from the cooled body to the heated section per unit time. The refrigerant, the material of the housing, and the flow path structure of the capillary flow path are provided such that all of the first, second, and fourth conditions are satisfied, or all of the first, third, and fourth conditions are satisfied.

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