KR102447779B1 - Sheet type heat pipe and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a sheet-type heat pipe and a method for manufacturing the same. (Woven Mesh), a wick disposed on the inner surface of the upper plate, and a refrigerant sealed in a vacuum in the inner space and having heat transfer characteristics due to phase change. The present invention has the advantage of being able to manufacture a heat pipe in the form of a thin sheet while having excellent sealing power, preventing distortion of the internal space, and having a structure capable of making the movement of the refrigerant wider and faster.

Description

Sheet-type heat pipe and its manufacturing method

The present invention relates to a sheet-type heat pipe used in a mobile device, and more particularly, to a sheet-type heat pipe that absorbs heat generated from an electronic component of a mobile device and radiates the absorbed heat in a direction opposite to the electronic component, and manufacturing thereof it's about how

As mobile devices gradually become smaller and higher in performance, the heat problem is becoming a serious problem. Mobile devices include smartphones and tablets.

A smartphone or tablet is equipped with an application processor (AP). An application processor is a small chip with a size of 1 to 2 cm, but like a computer's central processing unit (CPU), it is a core semiconductor that combines various functions such as a graphics processing unit (GPU), a communication chip, a sensor, a display, and multimedia into one.

Such an application processor is a key component that determines power consumption, and as time goes by, as the performance increases, heat factors continue to increase, requiring a technology to solve the heat problem.

In early smartphones, the application processor used a heat dissipation sheet to solve the heat problem, but in the 5G era, there is a problem that excessive heat is generated while supporting fast charging such as wireless charging. There is a problem that it is difficult to emit.

Therefore, recently, a pipe-shaped heat pipe with superior heat dissipation performance than a heat dissipation sheet has been discussed, but it is difficult to secure space to apply the pipe-shaped heat pipe to a slim smartphone. is demanding

Furthermore, in the case of 5G smartphones being commercialized recently, there is a problem of continuous battery consumption and heat generation due to battery consumption for informing when communication is not possible, so a sheet-type heat pipe capable of increasing heat dissipation efficiency is required.

Patent Document 1: No. 1992135 (registered on June 18, 2019)

An object of the present invention is to form an inner space between the upper and lower plates by bonding the upper and lower plates, and to seal the wick, woven mesh and refrigerant in the inner space to make the movement of the refrigerant wider and faster to improve heat dissipation efficiency. An object of the present invention is to provide a sheet-type heat pipe designed to be raised and a method for manufacturing the same.

Another object of the present invention is to provide a sheet-type heat pipe having a structure that prevents distortion of an internal space due to a pressure difference from atmospheric pressure while manufacturing a thin sheet-type heat pipe, and a method for manufacturing the same.

Another object of the present invention is to provide a sheet-type heat pipe and a method for manufacturing the same, which enable low-temperature brazing bonding between an upper plate and a lower plate, thereby enabling application of a membrane wick rather than a metal.

Another object of the present invention is to provide a sheet-type heat pipe capable of increasing heat dissipation efficiency by increasing thermal conductivity while reducing signal loss when applied to 5G electronic devices by maximally reducing metal, and a method for manufacturing the same.

Another object of the present invention is to provide a sheet-type heat pipe capable of forming an internal space therebetween using a flat plate-shaped upper plate and a lower plate, and a method for manufacturing the same.

Another object of the present invention is to provide a sheet-type heat pipe and a method for manufacturing the same, in which the condensed refrigerant falls and spreads well to facilitate the movement of the refrigerant.

According to a feature of the present invention for achieving the above object, the present invention provides a lower plate in contact with a heat source on the bottom surface, and the inner surface of the upper plate and the lower plate that are sealedly joined to the rim of the lower plate to form an inner space between the lower plate and the lower plate. Including woven mesh and wick placed on

There can be a gap between the wick and the woven mesh.

The refrigerant is water, and the refrigerant may be contained in the internal space by about 10 to 20% by volume.

The upper plate may be provided with a concave groove concave in the longitudinal direction on the inner surface, and a wick may be inserted into the concave groove.

The lower plate, the upper plate, the woven mesh, and the wick may be formed of copper or a copper alloy.

The lower plate, the upper plate, the woven mesh and the wick may have a thickness of 50 to 150 μm.

In order to form an inner space between the lower plate and the upper plate, at least one of the lower plate and the upper plate may have a rib protruding along the edge.

The woven mesh can be attached to the inner surface of the lower plate with a volatile adhesive.

The upper plate may be formed with a plurality of dots protruding toward the lower plate and in contact with the woven mesh.

In the dot, the first dot and the second dot having a smaller diameter than the first dot may be intersected.

The dots may be formed by photo-etching the upper plate.

The first embodiment of the present invention has a structure in which an inner space is formed by bonding the edges of a lower plate and an upper plate, a woven mesh is arranged on the lower surface of the inner space, and a wick is arranged on the upper surface. In addition to the rapid liquid diffusion, the vapor is rapidly absorbed and moved, so that the movement of the refrigerant is wider and faster, thereby increasing the heat dissipation efficiency.

In particular, in the first embodiment of the present invention, since the lower plate, the upper plate, the woven mesh, and the wick are formed of copper having high thermal conductivity, liquid diffusion and vapor movement are further accelerated to increase heat dissipation efficiency.

In addition, the first embodiment of the present invention has an effect that can contribute to increase the heat dissipation efficiency by making the movement of the refrigerant more smoothly because the dots having two sizes intersectingly serve as a support to prevent distortion of the inner space.

In addition, in the first embodiment of the present invention, since the edges of the lower plate and the upper plate are joined by high-temperature brazing using a high-temperature bonding material as a medium, the lower plate and the upper plate, which are thin in μm in thickness, can be sealed and joined, and accordingly, in the internal space. Since leakage of the injected refrigerant is prevented, it is possible to manufacture a sheet-type heat pipe having a thin thickness and excellent heat dissipation performance.

In addition, in the second embodiment of the present invention, since the edges of the lower plate and the upper plate are sealed and joined by low-temperature brazing using a low-temperature bonding material, the wick can be formed as a membrane wick having thermal conductivity while controlling the pore size. , there is an effect that can contribute to increasing the heat dissipation efficiency by making liquid diffusion and vapor movement faster.

Furthermore, in the low-temperature bonding substrate of the second embodiment of the present invention, the lower plate and the upper plate, which are thin in μm, can be sealed and joined by low-temperature brazing, thereby preventing leakage of the refrigerant injected into the inner space, so that the thickness is thin There is an effect that a sheet-type heat pipe having excellent heat dissipation performance can be manufactured.

In addition, in the third embodiment of the present invention, the lower plate and the upper plate are formed of a polymer-based material of low dielectric constant with increased thermal conductivity, and the lower wick and upper wick are formed of a membrane wick having thermal conductivity while adjusting the pore size. , it has the effect of increasing heat dissipation efficiency by reducing signal loss in 5G and increasing thermal conductivity to make liquid diffusion and vapor movement faster.

In addition, in the third embodiment of the present invention, since the edges of the lower plate and the upper plate are sealed and joined by low-temperature brazing using a low-temperature bonding material, the lower plate and the upper plate can be formed of a polymer-based material with a low dielectric constant, and the wick can be used as a membrane wick. It has a formable effect.

In addition, the low-temperature bonding substrate of the third embodiment of the present invention can seal-bond the lower plate and the upper plate, which are thin in ㎛ unit, by low-temperature brazing, thereby preventing leakage of the refrigerant injected into the internal space, so that the thickness is thin. There is an effect that a sheet-type heat pipe having excellent heat dissipation performance can be manufactured.

In addition, in the fourth embodiment of the present invention, since the gasket secures a space for the wick to be disposed between the lower plate and the upper plate, it is possible to form an internal space therebetween using a flat plate-shaped upper plate and a lower plate, and simple manufacturing The process has the effect of being able to manufacture a sheet-type heat pipe with a thin thickness and excellent heat dissipation performance.

In addition, in the fifth embodiment of the present invention, a hydrophobic coating layer is formed on the inner surfaces of the lower plate and the upper plate so that the condensed refrigerant falls well and spreads well, thereby making the movement of the refrigerant smoother, thereby increasing the heat dissipation efficiency.

1 is a view showing an example of attaching a sheet-type heat pipe according to the present invention on the application processor (AP) of the smartphone.
Figure 2 is a cross-sectional view taken along line AA' of Figure 1 according to the first embodiment of the present invention.
3 is a cross-sectional view taken along line BB′ of FIG. 1 according to the first embodiment of the present invention.
4 is an exploded cross-section taken along line B-B' of FIG. 1 as a first embodiment of the present invention.
FIG. 5 is a plan view showing the first embodiment of the present invention, after cutting FIG. 1 in the direction B-B'.
6 is another example of a cross-sectional view taken along line BB' of FIG. 1 according to the first embodiment of the present invention.
7 is a cross-sectional view taken along line AA′ of FIG. 1 according to a second embodiment of the present invention.
FIG. 8 is an exploded cross-section taken along line B-B' of FIG. 1 as a second embodiment of the present invention.
9 is a plan view showing a second embodiment of the present invention, after cutting FIG. 1 in the direction B-B'.
10 is a cross-sectional view taken along line AA′ of FIG. 1 according to a third embodiment of the present invention.
11 is an exploded cross-section taken along line B-B' of FIG. 1 as a third embodiment of the present invention;
FIG. 12 is a plan view showing a third embodiment of the present invention, after cutting FIG. 1 in the direction B-B'.
13 is an exploded cross-section taken along line B-B' of FIG. 1 as a fourth embodiment of the present invention.
14A to 14C are plan views showing the shape of a gasket according to a fourth embodiment of the present invention;
15 is an exploded cross-section taken along line B-B' of FIG. 1 as a fifth embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1 , the sheet-type heat pipe 100 according to the present invention is attached on the application processor (AP) 10 of the smartphone 1 and, when the temperature of the AP 10 rises, the refrigerant is converted to vapor. It functions to lower the temperature of the AP (10) by moving it away from the AP (10).

As the speed of the AP increases, the heat generated increases. For this reason, the performance of the heat pipe 100 for catching heat is very important. With the development of smartphones, users can turn on more applications at once and enjoy various functions quickly, but in order to achieve smooth performance, it is essential to prevent overheating of the AP.

As smartphones become more advanced, the importance of heat pipes increases.

Therefore, the sheet-type heat pipe 100 according to the present invention is manufactured in a sheet shape with a wider surface area compared to a conventional heat pipe formed of a straight tube to increase heat dissipation efficiency, and is applied to a smart phone that becomes thinner and thinner to make it easier to do. For example, the sheet-type heat pipe 100 may have a size of about 80×10 mm and a thickness of about 450 μm.

Since various embodiments are applied to the sheet-type heat pipe 100 according to the present invention in terms of material and internal structure, the first to fifth embodiments will be described.

[First embodiment]

As shown in FIG. 2 , the sheet-type heat pipe 100 according to the first embodiment has a lower plate 110 , an upper plate 120 , a woven mesh 130 , a wick 140 , and a refrigerant. (150).

The lower plate 110 and the upper plate 120 are positioned to face each other and the edges are sealed to form an inner space 101 between the inner surfaces facing each other. A woven mesh 130 and a wick 140 for inducing rapid liquid diffusion and rapid vapor movement are disposed in the inner space 101 , and a refrigerant 150 having heat transfer characteristics due to phase change is vacuum-sealed. For example, the refrigerant 150 may be made of water.

The sheet-type heat pipe 100 includes an inlet 170 for injecting a refrigerant. The inlet 170 is sealed after the injection of the refrigerant. In the sheet-type heat pipe 100 , the inner space 101 is sealed with a vacuum, and a refrigerant is injected while removing the vacuum in the inner space 101 . When the internal space 101 is vacuumed, the phase change of the refrigerant 150 proceeds at a temperature lower than atmospheric pressure, thereby increasing heat dissipation efficiency.

The refrigerant 150 may be contained in the internal space 101 by 10 to 20% by volume.

The lower plate 110 is in contact with a heat source on the bottom surface, and the upper plate 120 covers the upper part of the lower plate 110 to form an inner space 101 between the lower plate 110 and the lower plate 110 . The heat source may correspond to an AP or an antenna included in an electronic device such as a smartphone.

The sheet-type heat pipe 100 may be divided into an evaporation unit that absorbs a heat source, a connection unit that transmits absorbed heat in the opposite direction to the heat source, and a condensation unit that discharges the transferred heat.

In the sheet-type heat pipe 100 , a portion in contact with the heat source corresponds to the evaporator, the opposite side of the evaporator corresponds to the condensing portion, and a portion connecting the evaporator and the condensing portion corresponds to the connection portion. The evaporator, the connection part, and the condensing part are only demarcated in the drawings for convenience of description, and the boundaries are not clear.

The woven mesh 130 is attached to the inner surface of the lower plate 110 . Woven mesh 130 is for fast liquid diffusion. The woven mesh 130 is attached to the entire inner surface of the lower plate 110 excluding the edge. Since the sheet-type heat pipe 100 must have a space at the bottom for the liquid to flow, a woven mesh 130 having a form that can provide a space for the liquid to move is attached to the inner surface of the lower plate 110 . Since one side of the lower surface of the lower plate 110 is in contact with the heat source, the inner surface of the lower plate 110 becomes a passage through which the liquid flows. The woven mesh 130 has a fabric shape in which two strands of weft and warp are intersected and woven.

The wick 140 is attached to the inner surface of the upper plate 120 . The wick 140 is for fast vapor movement. The wick 140 is attached to the inner surface of the upper plate 120 in the longitudinal direction. The wick 140 causes capillary action to induce rapid vapor absorption and movement. The wick 140 has a fabric shape in which a weft thread and a warp thread are twisted. The wick 140 is made by twisting a braided copper wire. The braided copper wire absorbs the liquid quickly and moves to the state where it is contained, so the movement of the vapor is faster.

Since the woven mesh 130 has a form in which two copper wires are intersected and woven, it is less dense and has a lower density than the wick 140 in which the weft and warp threads are twisted.

The woven mesh 130 can secure a space for the liquid to move, thereby enabling rapid liquid diffusion. On the other hand, since the wick 140 absorbs and moves the vapor, a compact form without a space makes the movement of the vapor wider and faster.

The woven mesh 130 may have a wire diameter of about 50 μm and a mesh inner diameter of about 80 μm. The mesh inner diameter provides space for water to flow. The wick 140 may have a wire diameter of about 20 μm. Since the wick absorbs steam and moves, the wire diameter is smaller than that of the woven mesh 130 and does not provide a space for water to flow.

The lower plate 110 , the upper plate 120 , the woven mesh 130 , and the wick 140 may be formed of copper (Cu) or a copper alloy having high thermal conductivity. The copper alloy may be formed of one of 0.3%BeCu, QMET, and CuFeP. 0.3%BeCu is an alloy containing about 0.3wt% of Be and about 0.4wt% of Co in Cu, and QMET is an alloy containing about 0.1wt% of Ag, about 0.7wt% of Cr, and about 0.08wt% of Si in Cu. It is an alloy, and CuFeP is an alloy containing about 0.05 to 0.15 wt% of Fe and 0.025 to 0.04 wt% of P in Cu.

In the first embodiment, the lower plate 110, the upper plate 120, the woven mesh (Woven Mesh) 130 and the wick 140 will be described as an example formed of copper.

Copper has a high thermal conductivity, so the temperature rises faster and lowers easily than water. The amount of heat required to raise 1 g of a substance by 1 degree is called specific heat. Water has a specific heat of 1 cal, whereas copper has only 0.09 cal.

Water filled in the inner space 101 of the lower plate 110 and the upper plate 120 sealed in a vacuum state causes a capillary phenomenon and a phase change between gas-liquid and continuously circulates.

For example, when the AP is heated, the lower plate 110 made of copper in contact with the AP is heated and quickly transfers the temperature to the water. The water that has received heat from the lower plate 110 is heated and eventually vaporized to become steam. Since the vapor has a characteristic of moving at a low temperature, it moves to the condensing unit on the wick 140 attached to the upper plate 120 . The steam emits heat from the condensing unit and phase changes to water, and the water falls to the lower plate 110 by gravity. The water that has fallen to the lower plate 110 moves along the woven mesh 130 attached to the lower plate 110 to the evaporator with a high temperature again. As this process is automatically repeated, overheating of the AP can be prevented.

In this process, even if the temperature of the copper rises as the AP is heated, the internal overheating can be controlled because the temperature of the water in the inner space rises slowly. After that, when the copper is continuously heated, the water in the inner space of the sheet-type heat pipe 100 is changed to steam, thereby lowering the internal temperature once again. In addition, in the process of continuously circulating water while causing a phase change, the woven mesh 130 and the wick 140 cause capillary action with a large surface area to induce rapid water absorption and movement.

The wick 140 and the woven mesh 130 are spaced apart. A space is formed between the wick 140 and the woven mesh 130 and a space is formed therebetween, so that the phase-changed steam and water can move smoothly. The refrigerant 150 may be included in the internal space 101 in terms of volume ratio of about 10 to 20% in consideration of an increase in the volume of vapor according to the phase change.

3 and 4 , at least one of the lower plate 110 and the upper plate 120 is formed with ribs 111 and 121 protruding along the edges. The ribs 111 and 121 are for forming the inner space 101 between the lower plate 110 and the upper plate 120 . The ribs 111 and 121 serve as a support for forming the inner space 101 between the lower plate 110 and the upper plate 120 . The ribs 111 and 121 may be formed by etching the lower plate 110 and the upper plate 120 .

The woven mesh 130 is attached to the inner surface of the lower plate 110 with a volatile adhesive.

The volatile adhesive 135 may be melted in the process of high-temperature bonding of the edges of the lower plate 110 and the upper plate 120 to be described later to attach the woven mesh 130 to the inner surface of the lower plate 110 and volatilize.

The upper plate 120 has a concave groove 123 concave in the longitudinal direction is formed on the inner surface, and the wick 140 is inserted into the concave groove 123 . The wick 140 is disposed by being fitted to the concave groove 123 , but may be attached to the concave groove 123 with a volatile adhesive like the woven mesh 130 . The concave groove 123 is formed by etching the upper plate 120 .

A plurality of dots 125 protruding toward the lower plate 110 and contacting the woven mesh 130 are formed on the upper plate 120 . The dots 125 are disposed between the lower plate 110 and the upper plate 120 to serve as a support for preventing the inner space 101 from being crushed.

The dot 125 includes a first dot 125a and a second dot 125b having a smaller diameter than that of the first dot 125a.

Preferably, the dot 125 has a structure in which a plurality of first dots 125a and a plurality of second dots 125b having a smaller diameter than that of the first dot 125a are intersected. The structure in which the first dot 125a and the second dot 125b having a smaller diameter than that of the first dot 125a are intersected provides an internal space 101 sufficient to encapsulate the refrigerant 150, and increases the rigidity It prevents distortion of the inner space 101 due to the pressure difference from atmospheric pressure, and serves to increase heat dissipation efficiency by providing a wider flow path through which the refrigerant 150 moves.

The dot 125 is integrally formed with the upper plate 120 . The dots 125 are formed by photo-etching the upper plate 120 . The photo-etching may precisely form the dots 125 on the very thin upper plate 120 .

The dots 125 are formed to have a relatively thick thickness compared to the thickness of the wick 140 so that the wick 140 and the woven mesh 130 are spaced apart by a predetermined distance and a space is formed therebetween.

The lower plate 110 , the upper plate 120 , the woven mesh 130 , and the wick 140 may have a thickness in the range of 50 μm to 150 μm. For example, the lower plate 110 , the upper plate 120 , the woven mesh 130 , and the wick 140 may be formed to a thickness of 100 μm, and the dots 125 may be formed to a thickness of 150 μm.

The dots 125 may have a columnar shape having a circular cross-section or a substantially truncated cone shape with a diameter gradually decreasing toward the tip. The first dot 125a may have a radius R of the widest cross-sectional portion of 260 μm, and the second dot 125b may have a radius R of the widest cross-sectional portion of 170 μm.

As shown in FIG. 4 , the lower plate 110 and the upper plate 120 are joined to each other using a high-temperature bonding material 160 in a state where the edges are facing each other.

The high-temperature bonding substrate 160 may be formed on the front surface of the lower plate 110 or the upper plate 120 . Alternatively, the high-temperature bonding substrate 160 may be formed on the ribs 111 and 121 formed along the edges of the lower plate 110 or the upper plate 120 .

The high-temperature bonding substrate 160 is melted at a temperature of 900 to 1000° C. to bond the edges of the lower plate 110 and the upper plate 120 to each other. Preferably, it is melted at 950° C., which is the brazing temperature of the high-temperature bonding substrate 160 , to bond the edges of the lower plate 110 and the upper plate 120 . High-temperature bonding is intended to increase airtightness by increasing bonding strength in metal-to-metal bonding.

The high-temperature bonding substrate 160 is formed as a multi-layered thin film. The multi-layered thin film is intended to enhance the bonding strength by complementing the insufficient performance.

For example, the high-temperature bonding substrate 160 is a Ti sputter layer 160a formed by sputtering on the ribs 111 formed along the front surface or edge of the lower plate 110, and the Ti sputter layer 160a by sputtering on the upper portion. A Cu sputtered layer 160b formed, an Ag plating layer 160c formed by plating on the Cu sputtered layer 160b, and a Cu plating layer 160d formed by plating on the Ag plating layer 160c, and , and an Ag plating layer 160e formed by plating on the Cu plating layer 160d.

The Ti sputtered layer 160a is formed to a thickness of 0.2 μm, the Cu sputtered layer 160b is formed to a thickness of 0.5 μm, the Ag plating layer 160c is formed to a thickness of 3 μm, and the Cu plating layer 160d is 4 μm. , and the Ag plating layer 160e may be formed to a thickness of 3 μm.

Sputtering is for facilitating thin film formation. The plating may use electrospinning to form a uniform plating layer.

The thickness of each layer in the high-temperature bonding substrate 160 is designed in consideration of the coefficient of thermal expansion of each component. Cu and Ag are refractory metals.

A Ti sputter layer 160a is formed on the front surface of the lower plate 110 or on the ribs 111 for surface modification after cleaning since the base material must be clean before brazing.

The Cu sputtered layer 160b forms an intermetallic compound (CuTi) with the Ti sputtered layer 160a, and increases adhesion to the Ag plating layer 160c. In the bonding of Cu and Cu, Ag-Cu-Ag improves the wettability and adhesiveness by Ti, which is an active metal component, thereby improving bonding properties.

As shown in FIG. 5 , the lower plate 110 has a structure in which ribs 111 are formed along the edge. The rib 111 is formed by photo-etching a portion except for the edge of the lower plate 110 .

In FIG. 5 , the upper plate 120 has ribs 121 formed along the rim, and a concave groove 123 is formed in a predetermined area along the longitudinal direction in the center, and is formed on both sides based on the concave groove 123 . It has a structure in which one dot 125a and a second dot 125b having a smaller diameter than that of the first dot 125a are intersected.

In the upper plate 120, the rib 121, the concave groove 123, the first dot 125a, and the second dot 125b are formed by the rib 121, the first dot 125a, and the second dot 125b. It is formed by photo-etching the remaining part except for the part to be used. The concave groove 123 is etched to a greater depth of etching than other portions of the upper plate 120 .

The wick 140 is fitted and fixed in the concave groove 123 of the upper plate 120 , and the woven mesh 130 is fixed to the surface of the lower plate 110 except for the ribs 121 .

The lower plate 110 and the upper plate 120 are joined by high-temperature brazing in a state where the ribs 111 and 121 are abutted through the high-temperature bonding material 160 as a medium.

As shown in FIG. 6 , in the sheet-type heat pipe 100 ′, the ribs 111 may be formed only at the edge of the lower plate 110 . In this case, the rib 111 may have a deeper etching depth than when the ribs 111 and 121 are formed on both the edges of the lower plate 110 and the upper plate 120 .

Hereinafter, a method of manufacturing the sheet-type heat pipe according to the first embodiment will be described.

As shown in FIGS. 3 and 4 , the method of manufacturing a sheet-type heat pipe includes the steps of forming the lower plate 110 having ribs 111 formed along the edges, and the concave grooves 123 are formed along the longitudinal direction. Forming the upper plate 120 having a plurality of dots 125 formed on both sides of the lip groove 123 , and disposing the woven mesh 130 on the inner surface of the lower plate 110 , and the concave groove of the upper plate 120 . It includes the steps of disposing a wick on the 123 , and performing high-temperature brazing to seal and bond the edges of the lower plate 110 and the upper plate 120 .

The lower plate 110 , the upper plate 120 , the woven mesh 130 , and the wick 140 may be formed of copper (Cu) or a copper alloy having high thermal conductivity.

In the step of disposing the woven mesh 130 on the inner surface of the lower plate 110 , a volatile adhesive 135 is disposed between the inner surface of the lower plate 110 and the woven mesh 130 , and the volatile adhesive 135 is hot brazed It is melted in the process of performing the woven mesh 130 can be attached to the inner surface of the lower plate (110). For example, the volatile adhesive 135 may be a ceramic bond that is volatilized at about 200°C.

In the step of forming the lower plate 110 on which the ribs 111 are formed along the edges, the ribs 111 are formed by etching the lower plate 110 by photo-etching.

In the step of forming the upper plate 120 in which the concave groove 123 is formed along the longitudinal direction and the dot 125 is formed on both sides of the concave groove 123, the concave groove 123 and the dot 125 are formed in the upper plate 120 ) is formed by photo-etching.

The step of performing high-temperature brazing to seal and bond the edges of the lower plate 110 and the upper plate 120 is to form the high-temperature bonding substrate 160 on the edge of the lower plate 110 or the upper plate 120, Heat bonding is possible under temperature and vacuum conditions.

Preferably, the hot brazing is carried out at a temperature of 950°C. The high-temperature brazing temperature is a temperature at which the high-temperature bonding substrate 160 is melted, and the lower plate 110, the upper plate 120, the woven mesh 130 and the wick 140 are not melted.

The high-temperature bonding substrate 160 is an alloy capable of high-temperature brazing at a temperature of 950°C.

The high-temperature bonding substrate 160 is a Ti sputter layer 160a formed by sputtering along the edge of the lower plate 110 or the upper plate 120 and a Cu sputter layer formed by sputtering on the Ti sputter layer 160a. The Ag plating layer 160c formed by plating on the Cu sputtering layer 160b and the Cu plating layer 160d and the Cu plating layer 160d formed by plating on the Ag plating layer 160c by plating and an Ag plating layer 160e formed by plating.

The sheet-like heat pipe 100 includes an inlet 170 . After the high-temperature brazing step, the refrigerant 150 is injected into the inlet 170 and the inlet 170 is sealed. The refrigerant 150 is injected while removing the vacuum in the inner space 101 . The refrigerant 150 uses water having a higher specific heat than copper. The refrigerant 150 is injected into the inner space 101 to contain about 10 to 20% by volume.

Hereinafter, the operation of the first embodiment will be described.

The sheet-type heat pipe 100 according to the first embodiment is manufactured by four parts: a lower plate 110 , an upper plate 120 , a woven mesh 130 , and a wick 140 .

The sheet-type heat pipe 100 is formed by bonding the edges of the lower plate 110 and the upper plate 120 to form an inner space 101 therebetween, and a woven mesh 130 , a wick 140 and a wick 140 in the inner space 101 . It has a structure in which the refrigerant 150 is vacuum sealed.

In addition, the lower plate 110 , the upper plate 120 , the woven mesh 130 , and the wick 140 are formed of copper (Cu) or a copper alloy having high thermal conductivity, and the refrigerant 150 has specific heat compared to copper. Use this low water.

In the above structure, the woven mesh 130 can secure a space for the liquid to flow with high thermal conductivity, thereby enabling rapid liquid diffusion, and the wick 140 has a dense structure with high thermal conductivity to quickly vaporize the vapor. Since it is absorbed and moved, it is possible to increase the heat dissipation efficiency by making the movement of the refrigerant wider and faster.

In addition, a plurality of dots 125 protruding toward the lower plate 110 and contacting the woven mesh 130 are formed on the upper plate 120 . The dots 125 are disposed between the lower plate 110 and the upper plate 120 to serve as a support to prevent the inner space 101 from being crushed, so that the refrigerant moves more smoothly, thereby increasing the heat dissipation efficiency.

In addition, the edges of the lower plate 110 and the upper plate 120 are joined by high-temperature brazing via the high-temperature bonding substrate 160 .

High-temperature brazing can seal-bond the lower plate 110 and the upper plate 120, which are thin in μm units, and accordingly, the refrigerant 150 injected into the inner space 101 is prevented from leaking, so that the sheet-type heat has excellent heat dissipation performance. to be able to manufacture pipes.

[Second embodiment]

As shown in FIG. 7 , the sheet-type heat pipe 100a according to the second embodiment has a lower plate 110 , an upper plate 120 , a woven mesh 130 , a wick 140a and a refrigerant. (150).

The lower plate 110 and the upper plate 120 are positioned to face each other and the edges are sealed to form an inner space 101 between the inner surfaces facing each other. A woven mesh 130 and a wick 140a for inducing rapid liquid diffusion and rapid vapor movement are disposed in the inner space 101 , and a refrigerant 150 having heat transfer characteristics due to phase change is vacuum-sealed. The refrigerant 150 may be made of water.

The sheet-shaped heat pipe 100a includes an inlet 170 for injecting a refrigerant. The inlet 170 is sealed after the injection of the refrigerant. In the sheet-type heat pipe 100a, the inner space 101 is sealed with a vacuum, and a refrigerant is injected while the vacuum of the inner space 101 is removed. When the inner space 101 is vacuumed, the phase change of the refrigerant 150 proceeds at a temperature lower than atmospheric pressure, thereby increasing heat dissipation efficiency.

The refrigerant 150 may be contained in the internal space 101 by 10 to 20% by volume.

The lower plate 110 is in contact with a heat source on the bottom surface, and the upper plate 120 covers the upper part of the lower plate 110 to form an inner space 101 between the lower plate 110 and the lower plate 110 . The heat source may be an AP or an antenna chip.

The sheet-type heat pipe 100a may be divided into an evaporation unit that absorbs a heat source, a connection unit that transfers absorbed heat in the opposite direction to the heat source, and a condensation unit that discharges the transferred heat.

In the sheet-type heat pipe 100a, a portion in contact with a heat source corresponds to the evaporator, an opposite side of the evaporator corresponds to the condensing portion, and a portion connecting the evaporator and the condensing portion corresponds to the connection portion. The evaporator, the connection part, and the condensing part are only demarcated in the drawings for convenience of description, and the boundaries are not clear.

The woven mesh 130 is attached to the inner surface of the lower plate 110 . Woven mesh 130 is for liquid diffusion over a large area quickly. When a liquid spreads over a large area, it vaporizes well. The woven mesh 130 is attached to the entire inner surface of the lower plate 110 excluding the edge. Since the sheet-type heat pipe 100a must have a space at the bottom for the liquid to flow, a woven mesh 130 having a form that can provide a space for the liquid to move is attached to the inner surface of the lower plate 110 . Since the bottom surface of the lower plate 110 is in contact with the heat source, the inner surface of the lower plate 110 becomes a passage through which the liquid flows. The woven mesh 130 has a fabric shape in which two strands of weft and warp are intersected and woven.

The wick 140a is attached to the inner surface of the upper plate 120 . The wick 140a causes capillary action and is for fast vapor movement. The wick 140a is attached to the inner surface of the upper plate 120 in the longitudinal direction. The wick 140a causes capillary action to induce rapid vapor absorption and movement. When capillary action occurs, steam moves quickly and cools quickly. The wick 140a has a fabric shape in which a weft thread and a warp thread are twisted. The wick 140a is also called a braided thread. Since the braid moves in a state of moisture, it speeds up the movement of steam. The wick 140a is a membrane wick formed by electroless plating on a nanofiber membrane. The membrane wick can form a dense structure like a braided thread by adjusting the pore size.

Since the woven mesh 130 has a form in which two strands are intersected and woven, it is less dense and has a lower density than the wick 140a in which the weft and warp threads are twisted. Therefore, the woven mesh 130 can secure a space for the liquid to move, enabling rapid liquid diffusion. On the other hand, since the wick 140a absorbs and moves the vapor, a dense form without a space absorbs the vapor quickly, thereby making the movement of the vapor wider and faster.

The woven mesh 130 may have a wire diameter of about 50 μm and a mesh inner diameter of about 80 μm. The mesh inner diameter provides space for water to flow. The wick 140a may have a wire diameter of about 20 μm. Since the wick absorbs steam and moves, the wire diameter is smaller than that of the woven mesh 130 and does not provide a space for water to flow.

The lower plate 110 and the upper plate 120 are formed of a metal material. Preferably, the lower plate 110 and the upper plate 120 are formed of copper (Cu) or a copper alloy having high thermal conductivity. For example, the lower plate 110 and the upper plate 120 may use oxygen-free plated copper. The copper alloy may be formed of one of 0.3%BeCu, QMET, and CuFeP. 0.3%BeCu is an alloy containing about 0.3wt% of Be and about 0.4wt% of Co in Cu, and QMET is an alloy containing about 0.1wt% of Ag, about 0.7wt% of Cr, and about 0.08wt% of Si in Cu. It is an alloy, and CuFeP is an alloy containing about 0.05 to 0.15 wt% of Fe and 0.025 to 0.04 wt% of P in Cu.

The woven mesh 130 may be formed of copper (Cu) or a copper alloy having high thermal conductivity.

The wick 140a uses a membrane wick formed by electroless plating on a nanofiber membrane. The nanofiber membrane may be a polyvinylidene fluoride (PVDF) nanofiber membrane.

Electroless plating can be performed with a metal having excellent thermal conductivity, such as copper or nickel. In addition to the electroless plating, at least one of aluminum, silver, titanium, chromium, gold, carbon, iron, platinum, and graphite or an alloy of two or more thereof may be used.

The PVDF nanofiber membrane has a thin and uniform pore distribution with a fiber thickness of 0.2 to 0.3 μm. When the wick 140a is formed of a membrane wick formed by plating copper or nickel on the surface of the PVDF nanofiber membrane, the pore size can be adjusted while having the same thermal conductivity as a metal, so that the movement speed of the refrigerant can be increased.

Copper forming the lower plate 110 and the upper plate 120 has a high thermal conductivity, so the temperature rises faster than water and falls easily. The amount of heat required to raise 1 g of a substance by 1 degree is called specific heat. Water has a specific heat of 1 cal, whereas copper has only 0.09 cal.

Water filled in the inner space 101 of the lower plate 110 and the upper plate 120 sealed in a vacuum state causes a capillary phenomenon and a phase change between gas-liquid and continuously circulates.

For example, when the AP is heated, the lower plate 110 made of copper in contact with the AP is heated and quickly transfers the temperature to the water. The water that has received heat from the lower plate 110 is heated and eventually vaporized to become steam. Since the vapor has a characteristic of moving at a low temperature, it moves to the condensing unit on the wick 140a attached to the upper plate 120 . The steam emits heat from the condensing unit and phase changes to water, and the water falls to the lower plate 110 by gravity. The water that has fallen to the lower plate 110 moves along the woven mesh 130 attached to the lower plate 110 to the evaporator with a high temperature again. As this process is automatically repeated, overheating of the AP can be prevented.

In this process, even if the temperature of the copper rises as the AP is heated, the internal overheating can be controlled because the temperature of the water in the inner space rises slowly. After that, when copper is continuously heated, the water in the inner space of the sheet-type heat pipe 100a changes to steam, thereby lowering the internal temperature once again. In addition, in the process of continuously circulating water while causing a phase change, the woven mesh 130 and the wick 140a cause capillary action with a large surface area to induce rapid water absorption and movement.

Furthermore, since the wick 140a is a membrane wick formed by plating copper or nickel on the surface of the PVDF nanofiber membrane, it is manufactured in a structure that accelerates moisture absorption through pore size control, thereby inducing more rapid moisture absorption and movement to dissipate heat. performance can be increased.

The wick 140a and the woven mesh 130 are spaced apart. A space is formed between the wick 140a and the woven mesh 130 and a space is formed therebetween, so that the phase-changed steam and water can move smoothly. The refrigerant 150 is included in the internal space 101 in terms of volume ratio of about 10 to 20% in consideration of an increase in the volume of vapor according to the phase change.

7 and 8 , at least one of the lower plate 110 and the upper plate 120 is formed with ribs 111 and 121 protruding along the edges. The ribs 111 and 121 are for forming the recessed inner space 101 between the lower plate 110 and the upper plate 120 . The ribs 111 and 121 serve as a support for forming the inner space 101 between the lower plate 110 and the upper plate 120 . The ribs 111 and 121 may be formed by etching (etching) the lower plate 110 and the upper plate 120 .

In addition, the ribs 111 formed on the lower plate 110 well seat the woven mesh 130 therebetween.

The woven mesh 130 may be attached to the inner surface of the lower plate 110 with a volatile adhesive.

The volatile adhesive 135 may be melted in the process of low-temperature bonding of the edges of the lower plate 110 and the upper plate 120 to be described later to attach the woven mesh 130 to the inner surface of the lower plate 110 and volatilize.

The upper plate 120 is provided with a concave groove 123 concave in the longitudinal direction on the inner surface, and the wick 140a is inserted into the concave groove 123 to be disposed. The wick 140a is disposed by being fitted to the concave groove 123 , but may be attached to the concave groove 123 with a volatile adhesive like the woven mesh 130 . The concave groove 123 may be formed by etching the upper plate 120 .

A plurality of dots 125 protruding toward the lower plate 110 and contacting the woven mesh 130 are formed on the upper plate 120 . The dots 125 are disposed between the lower plate 110 and the upper plate 120 to secure the inner space 101 and serve as a support for preventing the inner space 101 from being crushed.

The dot 125 includes a first dot 125a and a second dot 125b having a smaller diameter than that of the first dot 125a. Preferably, the dot 125 has a structure in which a plurality of first dots 125a and a plurality of second dots 125b having a smaller diameter than that of the first dot 125a are intersected. The structure in which the first dot 125a and the second dot 125b having a smaller diameter than that of the first dot 125a are intersected provides an internal space 101 sufficient to encapsulate the refrigerant 150, and increases the rigidity It prevents distortion of the inner space 101 due to the pressure difference from atmospheric pressure, and serves to increase heat dissipation efficiency by providing a wider flow path through which the refrigerant 150 moves.

The dot 125 is integrally formed with the upper plate 120 . The dots 125 are formed by photo-etching the upper plate 120 . The photo-etching may precisely form the dots 125 on the very thin upper plate 120 .

The dots 125 are formed to have a relatively thick thickness compared to the thickness of the wick 140a so that the wick 140a and the woven mesh 130 are spaced apart by a predetermined distance and a space is formed therebetween.

The lower plate 110 , the upper plate 120 , the woven mesh 130 , and the wick 140a may have a thickness in the range of 50 μm to 150 μm. For example, the lower plate 110 , the upper plate 120 , the woven mesh 130 , and the wick 140a may be formed to a thickness of 100 μm, and the dots 125 may be formed to a thickness of 150 μm.

The dots 125 may have a columnar shape having a circular cross-section or a substantially truncated cone shape with a diameter gradually decreasing toward the tip. The first dot 125a may have a radius R of the widest cross-sectional portion of 260 μm, and the second dot 125b may have a radius R of the widest cross-sectional portion of 170 μm.

As shown in FIG. 8 , the lower plate 110 and the upper plate 120 are joined at a low temperature using the low-temperature bonding substrate 180 in a state where the edges are facing each other.

The low-temperature bonding substrate 180 may be formed of a sputtering lower plate 110 of silver on the ribs 111 and 121 formed along the edges of the lower plate 110 or the upper plate 120 . Alternatively, the low-temperature bonding substrate 180 may be formed on the entire surface of the lower plate 110 or the upper plate 120 by a sputtering method.

When the low-temperature bonding substrate 180 is formed on the entire surface of the lower plate 110 or the upper plate 120, the edges of the lower plate 110 and the upper plate 120 are joined in the low-temperature bonding process and the wick 140a is formed on the upper plate 120 at the same time. ) is bonded to the inner surface, and the woven mesh 130 may also have a function of being joined to the inner surface of the lower plate 110 .

The low-temperature bonding substrate 180 is melt-bonded at the edge of the lower plate 110 and the upper plate 120 at a temperature of 200 ~ 300 ℃. Preferably, with the lower plate 110 and the upper plate 120 facing each other, the edge is joined by heating at 250° C., which is the brazing temperature of the low-temperature bonding substrate 180 .

The low-temperature bonding is to enable the application of a membrane wick that is not a metal to the wick 140a. When the wick 140a is manufactured as a membrane wick, the pore size can be adjusted to a desired size, but the wick loses its function because the melting temperature is low and the wick melts during high-temperature bonding. Therefore, it is possible to apply a membrane wick capable of adjusting the pore size of the wick 140a only when low-temperature bonding is possible.

The low-temperature bonding substrate 180 is formed of a sputtered thin film having a multi-layer structure. The multi-layered thin film is intended to enhance the bonding strength by complementing the insufficient performance.

The low-temperature bonding substrate 180 is a Ti sputter layer 180a and a Ti sputter layer formed on one of the front surfaces of the lower plate 110 and the upper plate 120 or one of the ribs 111 and 121 of the lower plate 110 and the upper plate 120 . A SnAg sputter layer 180b formed on the 180a is included. The multilayer structure of the Ti sputter layer 180a and the SnAg sputter layer 180b is a component that is brazed at a low temperature.

The SnAg sputter layer contains 95 to 98 wt% of Sn and 3 to 5 wt% of Ag. Preferably, the SnAg sputter layer consists of 97 wt% Sn and 3 wt% Ag.

The Ti sputter layer 180a may be formed to a thickness of 0.2 μm, and the SnAg sputter layer 180b may be formed to a thickness of 1 μm.

The thickness of each layer in the low-temperature bonding substrate 180 is designed in consideration of the coefficient of thermal expansion of each component, and when the thickness of each layer is designed, the bonding strength between the lower plate 110 and the upper plate 120 is increased. SnAg is a low melting point metal and has good wettability with copper.

For example, the Ti sputter layer 180a is formed on the ribs 111 of the lower plate 110 for surface modification after washing because the base material must be clean before brazing for good bonding.

The Ti sputtered layer 180a forms an intermetallic compound (CuTi) with Cu, and adhesion to the SnAg sputtered layer 180b is increased. In the bonding of the SnAg sputter layer 180b and Cu, SnAg forms a Sn-Ag-Cu-based intermetallic compound to improve wettability and adhesion, thereby improving bonding properties.

As shown in FIG. 9 , the lower plate 110 has a structure in which ribs 111 are formed along the edge. The rib 111 is formed by photo-etching a portion except for the edge of the lower plate 110 .

The upper plate 120 has a rib 121 formed along the edge, a concave groove 123 is formed in a predetermined area along the longitudinal direction in the center, and first dots 125a on both sides based on the concave groove 123 . ) and the second dot 125b having a smaller diameter than the first dot 125a have a structure in which they are intersected.

In the upper plate 120, the rib 121, the concave groove 123, the first dot 125a, and the second dot 125b are formed by the rib 121, the first dot 125a, and the second dot 125b. It is formed by etching the remaining part except for the part to be formed by photo-etching. The concave groove 123 is formed to have a deeper etching depth than other portions of the upper plate 120 .

The wick 140a is fitted and fixed to the concave groove 123 of the upper plate 120 , and the woven mesh 130 is fixed to the surface of the lower plate 110 except for the ribs 121 .

The lower plate 110 and the upper plate 120 are joined by low-temperature brazing in a state in which the ribs 111 and 121 face each other through the low-temperature bonding substrate 180 .

In the second embodiment, the ribs 111 and 121 have been described as an example in which the ribs 111 and 121 are formed on the edges of the lower plate and the upper plate, respectively, but the ribs 111 may be formed only on the edges of the lower plate 110 .

Hereinafter, a method of manufacturing the sheet-type heat pipe according to the second embodiment will be described.

7 and 8, the method of manufacturing a sheet-type heat pipe includes the steps of forming the lower plate 110 having ribs 111 formed along the edge, and concave grooves 123 are formed along the longitudinal direction. Forming the upper plate 120 having a plurality of dots 125 formed on both sides of the lip groove 123 , and disposing the woven mesh 130 on the inner surface of the lower plate 110 , and the concave groove of the upper plate 120 . It includes the steps of arranging a wick on the 123 , and performing low-temperature brazing to seal and bond the edges of the lower plate 110 and the upper plate 120 .

The lower plate 110 and the upper plate 120 are formed of copper (Cu) or a copper alloy having high thermal conductivity. The woven mesh 130 is formed of copper (Cu) or a copper alloy having high thermal conductivity.

The wick 140a is formed of a PVDF nanofiber membrane so that the pore size can be adjusted, and the surface is electroless-plated with copper or nickel to have electrical conductivity and thermal conductivity.

In the step of disposing the woven mesh 130 on the inner surface of the lower plate 110 , a volatile adhesive 135 is disposed between the inner surface of the lower plate 110 and the woven mesh 130 . The volatile adhesive 135 may be melted in the process of performing low-temperature brazing to attach the woven mesh 130 to the inner surface of the lower plate 110 . For example, the volatile adhesive 135 may be a ceramic bond that is volatilized at about 200°C.

In the step of forming the lower plate 110 on which the ribs 111 are formed along the edges, the ribs 111 are formed by photo-etching the lower plate 110 .

In the step of forming the upper plate 120 in which the concave groove 123 is formed along the longitudinal direction and the dot 125 is formed on both sides of the concave groove 123, the concave groove 123 and the dot 125 are formed in the upper plate 120 ) is formed by photo-etching.

In the step of performing low-temperature brazing to seal and bond the edges of the lower plate 110 and the upper plate 120 , the low-temperature bonding substrate 180 is formed on the edge of the lower plate 110 or the upper plate 120 , or the lower plate 110 or A low-temperature bonding substrate 180 is formed on the front surface of the upper plate 120, and heat-bonded at a temperature of 200 to 300°C. Preferably, the low-temperature brazing is carried out at a temperature of 250°C.

The low-temperature bonding substrate 180 is a Ti sputter layer 180a formed by sputtering along the front surface of at least one of the lower plate 110 and the upper plate 120 or along the edge of at least one of the lower plate 110 and the upper plate 120 and Ti sputtering. A SnAg sputtering layer 180b formed by sputtering is included on the layer 180a.

The sheet-shaped heat pipe 100a includes an inlet 170 . After the low-temperature brazing step, the refrigerant 150 is injected into the inlet 170 and the inlet 170 is sealed. The refrigerant 150 is injected while removing the vacuum in the inner space 101 . The refrigerant 150 uses water having a higher specific heat than copper. The refrigerant 150 may be injected into the inner space 101 so as to contain about 10 to 20% by volume.

Hereinafter, the operation of the second embodiment will be described.

The sheet-type heat pipe 100a according to the second embodiment is manufactured from four parts: a lower plate 110 , an upper plate 120 , a woven mesh 130 , and a wick 140a.

The sheet-type heat pipe 100a is formed by bonding the edges of the lower plate 110 and the upper plate 120 to form an inner space 101 therebetween, and a woven mesh 130 and a wick 140a in the inner space 101. It has a structure in which the refrigerant 150 is vacuum sealed.

In addition, the lower plate 110 , the upper plate 120 , and the woven mesh 130 are formed of copper (Cu) having high thermal conductivity, and the wick 140a applies a membrane wick with an adjustable pore size, and the refrigerant 150 . uses water with a lower specific heat than copper.

In the above structure, the woven mesh 130 can secure a space for the liquid to flow with high thermal conductivity, thereby enabling rapid liquid diffusion, and the wick 140a has a denser structure with thermal conductivity to quickly vaporize the vapor. Since it is absorbed and moved quickly, the heat dissipation efficiency can be increased by making the movement of the refrigerant through phase change wider and faster.

In addition, the sheet-type heat pipe 100a has a structure in which a plurality of dots 125 protruding from the upper plate 120 toward the lower plate 110 and contacting the woven mesh 130 are formed. These dots 125 are disposed between the lower plate 110 and the upper plate 120 to serve as a support to prevent the inner space 101 from being crushed, so it can contribute to improving the heat dissipation efficiency by making the refrigerant move more smoothly. .

In addition, the lower plate 110 and the upper plate 120 are etched to secure a space in which the woven mesh 130 and the wick 140a are to be arranged, and the dot 125 is formed on the upper plate 120, so that the process can be simplified. And it is possible to manufacture a thin sheet-type heat pipe (100a) in the unit of ㎛ thickness.

In addition, in the sheet-type heat pipe 100a, the edges of the lower plate 110 and the upper plate 120 are joined by low-temperature brazing via the low-temperature bonding substrate 180 .

Low-temperature brazing is possible by the low-temperature bonding substrate 180 including the Ti sputter layer 180a and the SnAg sputter layer 180b formed by sputtering on the Ti sputter layer 180a. This low-temperature bonding substrate 180 can seal and bond the lower plate 110 and the upper plate 120, which are thin in μm units, uniformly, without a difference in the height of the internal components at low temperatures, and, accordingly, injected into the inner space 101. It is possible to quickly move the refrigerant 150 and prevent leakage, so that a sheet-type heat pipe having excellent heat dissipation performance can be manufactured.

[Third embodiment]

As shown in FIG. 10 , the sheet-type heat pipe 100b according to the third embodiment has a lower plate 110b, an upper plate 120b, a lower wick 130b, an upper wick 140b, and a refrigerant. (150).

The lower plate 110b and the upper plate 120b are positioned to face each other and the edges are sealed to form an inner space 101 between the inner surfaces facing each other. A lower wick 130b and an upper wick 140b for inducing rapid liquid diffusion and rapid vapor movement are disposed in the inner space 101 , and a refrigerant 150 having heat transfer characteristics due to phase change is vacuum-sealed. The refrigerant 150 may be made of water.

The sheet-shaped heat pipe 100b includes an inlet 170 for injecting a refrigerant. The inlet 170 is sealed after the injection of the refrigerant. In the sheet-type heat pipe 100b, the inner space 101 is sealed with a vacuum, and a refrigerant is injected while the vacuum of the inner space 101 is removed. When the internal space 101 is vacuumed, the phase change of the refrigerant 150 proceeds at a temperature lower than atmospheric pressure, thereby increasing heat dissipation efficiency.

The refrigerant 150 may be contained in the internal space 101 by 10 to 20% by volume.

The lower plate 110b has one bottom surface in contact with the heat source, and the upper plate 120b covers the upper part of the lower plate 110b to form an internal space 101 between the lower plate 110 and the lower plate 110b. The heat source may be an electronic component such as an AP or an antenna chip.

The sheet-type heat pipe 100b may be divided into an evaporation unit that absorbs a heat source, a connection unit that transmits absorbed heat in the opposite direction to the heat source, and a condensation unit that discharges the transferred heat.

In the sheet-type heat pipe 100b, a portion in contact with a heat source corresponds to the evaporator, an opposite side of the evaporator corresponds to the condensing portion, and a portion connecting the evaporator and the condensing portion corresponds to the connection portion. The evaporator, the connection part, and the condensing part are only demarcated in the drawings for convenience of description, and the boundaries are not clear.

The lower wick 130b is attached to the inner surface of the lower plate 110b. The lower wick 130b is for fast and large area liquid diffusion. When a liquid spreads over a large area, it vaporizes well. The lower wick 130b is attached to the entire inner surface of the lower plate 110b except for the edge. Since the sheet-type heat pipe 100b must have a space at the bottom for the liquid to flow, a lower wick 130b having a shape that can provide a space for the liquid to move is attached to the inner surface of the lower plate 110b.

Since the bottom surface of the lower plate 110b is in contact with the heat source, the inner surface of the lower plate 110b becomes a passage through which the liquid flows. The lower wick 130b is a membrane wick formed by electroless plating on a nanofiber membrane, and may control a pore size to form a passage through which a liquid flows.

The upper wick 140b is attached to the inner surface of the upper plate 120b. The upper wick 140b causes capillary action and is for fast vapor movement. The upper wick 140b is attached to the inner surface of the upper plate 120b in the longitudinal direction. The upper wick 140b causes capillary action to induce rapid vapor absorption and movement. When capillary action occurs, the vapor moves rapidly and the cooling is also rapid. The upper wick 140b has a fabric shape in which a weft thread and a warp thread are twisted. The upper wick 140b is also called a braided thread. As the braid moves in a state of moisture, it speeds up the movement of steam. The upper wick 140b is a membrane wick formed by electroless plating on a nanofiber membrane, and can form a dense structure like a skein of braided yarn by adjusting the pore size.

The lower wick 130b has a large pore size so that a liquid can flow, and the upper wick 140b has a small pore size so that it can absorb vapor and move, so that it is dense and dense.

The lower wick 130b has large pores to secure a space for the liquid to move, thereby enabling rapid liquid diffusion. On the other hand, since the upper wick 140b absorbs and moves the vapor, the compact form without a space due to the small pores absorbs the vapor quickly, thereby making the movement of the vapor wider and faster.

The lower wick 130b may have a wire diameter of about 50 μm and pores of about 80 μm. The pores provide space for water to flow. The upper wick 140b may have a wire diameter of about 20 μm. Since the upper wick 140b absorbs steam and moves, the wire diameter is smaller than that of the lower wick 130b and does not provide a space through which water can flow.

The lower plate 110b and the upper plate 120b are formed of a polymer-based material.

A polymer-based material is one in which a low dielectric constant polymer is mixed with a ceramic filler to increase thermal conductivity. The ceramic filler is preferably boron nitride. The low dielectric constant polymer may be one of low dielectric constant polypropylene (PP) and polyethylene (PE). Polyimide (PI) is not preferable because of its high dielectric constant.

In the embodiment, the upper plate 120b and the lower plate 110b are formed by mixing boron nitride as a ceramic filler with polypropylene (PP). Polypropylene lowers the dielectric constant to reduce frequency loss in 5G, and boron nitride increases thermal conductivity to increase heat dissipation efficiency.

In 5G, it is better to use metal for antenna heat dissipation, but metal has a large signal loss and rapidly degrades antenna characteristics. Therefore, in 5G, a polymer-based material with a low dielectric constant with increased thermal conductivity is used to reduce metals as much as possible.

Graphite or zirconia may be mixed to increase the thermal conductivity of the polymer, but graphite and zirconia are not preferable because their dielectric constant is high and signal loss is large.

The lower wick 130b and the upper wick 140b use membrane wicks formed by electroless plating on a nanofiber membrane. The nanofiber membrane may be a polyvinylidene fluoride (PVDF) nanofiber membrane. Electroless plating can be performed with a metal having excellent thermal conductivity, such as copper or nickel.

The PVDF nanofiber membrane has a thin fiber thickness and a uniform pore distribution. When the upper wick 140b is formed of a membrane wick formed by plating copper or nickel on the surface of the PVDF nanofiber membrane, the pore size can be adjusted while having the same thermal conductivity as a metal, thereby speeding the movement of the refrigerant. .

For example, by adjusting the pore sizes of the lower wick 130b and the upper wick 140b, it is possible to enable rapid diffusion of liquid and rapid movement and diffusion of vapor.

Since the polymer-based material forming the lower plate 110b and the upper plate 120b includes boron nitride and has high thermal conductivity, the temperature rises faster than water and easily lowers.

Water filled in the inner space 101 of the lower plate 110b and the upper plate 120b sealed in a vacuum state causes a capillary phenomenon and a phase change between gas-liquid and continuously circulates.

For example, when the AP is heated, the lower plate 110b in contact with the AP is heated while quickly transferring the temperature to the water. The water that has received heat from the lower plate 110b is heated and eventually vaporized to become steam. Since the vapor has a characteristic of moving at a low temperature, it moves to the condensing unit on the upper wick 140b attached to the upper plate 120b. The steam emits heat from the condensing unit and phase changes to water, and the water falls to the lower plate 110b by gravity. The water that has fallen to the lower plate 110b moves along the lower wick 130b attached to the lower plate 110b to the evaporator having a high temperature again. As this process is automatically repeated, overheating of the AP can be prevented.

In this process, even if the AP is heated and the temperature of the lower plate 110b and the upper plate 120b rises, the temperature of the water in the inner space rises slowly, so that internal overheating can be controlled. Afterwards, when the lower plate 110b and the upper plate 120b are continuously heated, the water in the inner space of the sheet-type heat pipe 100b changes to steam, thereby lowering the internal temperature once again. In addition, in the process of continuously circulating water with a phase change, the lower wick 130b and the upper wick 140b cause capillary action with a large surface area to induce rapid water absorption and movement.

Furthermore, since the lower wick 130b and the upper wick 140b are membrane wicks formed by plating copper or nickel on the surface of the PVDF nanofiber membrane, it is possible to obtain moisture more quickly when fabricated with a structure that accelerates moisture absorption through pore size control. By inducing absorption and movement, heat dissipation performance can be improved.

The upper wick 140b and the lower wick 130b are spaced apart. A space is formed between the upper wick 140b and the lower wick 130b and a space is formed therebetween, so that the phase-changed steam and water can smoothly move. The refrigerant 150 may be included in the internal space 101 in terms of volume ratio of about 10 to 20% in consideration of an increase in the volume of vapor according to the phase change.

3 and 4 , at least one of the lower plate 110b and the upper plate 120b is formed with ribs 111 and 121 protruding along the edges. The ribs 111 and 121 are for forming the recessed inner space 101 between the lower plate 110b and the upper plate 120b. The ribs 111 and 121 serve as a support for forming the inner space 101 between the lower plate 110b and the upper plate 120b. The ribs 111 and 121 may be integrally formed with the lower plate 110b and the upper plate 120b during injection molding.

In addition, the ribs 111 formed on the lower plate 110b well seat the lower wick 130b therebetween.

The lower wick 130b may be attached to the inner surface of the lower plate 110b with a volatile adhesive.

The volatile adhesive 135 may be melted in the process of low-temperature bonding of the edges of the lower plate 110b and the upper plate 120b to be described later to attach the lower wick 130b to the inner surface of the lower plate 110b and volatilize.

The upper plate 120b is provided with a concave groove 123 concave in the longitudinal direction on the inner surface, and the upper wick 140b is inserted into the concave groove 123 . The upper wick 140b is disposed by being fitted into the concave groove 123 , but may be attached to the concave groove 123 with a volatile adhesive like the lower wick 130b. The concave groove 123 may be integrally formed during injection molding of the upper plate 120b.

A plurality of dots 125 protruding toward the lower plate 110b and contacting the lower wick 130b are formed on the upper plate 120b. The dots 125 are disposed between the lower plate 110b and the upper plate 120b to secure the inner space 101 and serve as a support for preventing the inner space 101 from being crushed.

The dot 125 includes a first dot 125a and a second dot 125b having a smaller diameter than that of the first dot 125a. Preferably, the dot 125 has a structure in which a plurality of first dots 125a and a plurality of second dots 125b having a smaller diameter than that of the first dot 125a are intersected. The structure in which the first dot 125a and the second dot 125b having a smaller diameter than that of the first dot 125a are intersected provides an internal space 101 sufficient to encapsulate the refrigerant 150, and increases the rigidity It prevents distortion of the inner space 101 due to the pressure difference from atmospheric pressure, and serves to increase heat dissipation efficiency by providing a wider flow path through which the refrigerant 150 moves.

The dot 125 is integrally formed with the upper plate 120b. The dots 125 are integrally formed during injection molding of the upper plate 120b. Injection molding can precisely form the dots 125 on the very thin upper plate 120b.

The dots 125 are formed to have a relatively thick thickness compared to the thickness of the upper wick 140b so that the upper wick 140b and the lower wick 130b are spaced apart by a predetermined distance and a space is formed therebetween.

The lower plate 110b, the upper plate 120b, the lower wick 130b, and the upper wick 140b may have a thickness in a range of 50 μm to 150 μm. For example, the lower plate 110b, the upper plate 120b, the lower wick 130b, and the upper wick 140b may be formed to a thickness of 100 μm, and the dots 125 may be formed to a thickness of 150 μm.

The dots 125 may have a columnar shape having a circular cross-section or a substantially truncated cone shape with a diameter gradually decreasing toward the tip. The first dot 125a may have a radius R of the widest cross-sectional portion of 260 μm, and the second dot 125b may have a radius R of the widest cross-sectional portion of 170 μm.

As shown in FIG. 11 , the lower plate 110b and the upper plate 120b are joined at a low temperature using the low-temperature bonding substrate 180 in a state where the edges are facing each other.

The low-temperature bonding substrate 180 may be formed by sputtering on the ribs 111 and 121 formed along the edges of the lower plate 110b or the upper plate 120b. Alternatively, the low-temperature bonding substrate 180 may be formed on the entire surface of the lower plate 110b or the upper plate 120b by sputtering.

When the low-temperature bonding substrate 180 is formed on the entire surface of the lower plate 110b or the upper plate 120b, the edges of the lower plate 110b and the upper plate 120b are joined in the low-temperature bonding process, and at the same time, the upper wick 140b is formed on the upper plate ( 120b), and the lower wick 130b may also have a function of bonding to the inner surface of the lower plate 110b.

The low-temperature bonding substrate 180 is melt-bonded at the edge of the lower plate 110b and the upper plate 120b at a temperature of 200 ~ 300 ℃. Preferably, the lower plate 110b and the upper plate 120b are heated at 250° C., which is the brazing temperature of the low-temperature bonding substrate 180, in a state where the edge is joined to the edge.

The low-temperature bonding allows the lower plate 110b and the upper plate 120b to be formed of a polymer-based material. In addition, the low-temperature bonding enables the application of a membrane wick rather than a metal to the lower wick 130b and the upper wick 140b.

If the lower plate 110b and the upper plate 120b are formed of a polymer-based material of low dielectric constant with increased thermal conductivity, it is possible to manufacture a sheet-type heat pipe that does not affect the antenna characteristics by preventing signal loss in 5G, but the lower plate 110b ) and the lower melting temperature of the upper plate 120b, low-temperature bonding should be possible.

In addition, if the lower wick 130b and the upper wick 140b are made of a membrane wick, the pore size can be adjusted to a desired size. Therefore, only when low-temperature bonding is possible, the upper wick 140b is manufactured as a membrane wick capable of adjusting the pore size, and thus can be applied to the sheet-type heat pipe 100b.

The low-temperature bonding substrate 180 is formed of a sputtered thin film having a multi-layer structure. The multi-layered thin film is intended to enhance the bonding strength by complementing the insufficient performance.

The low-temperature bonding substrate 180 is a Ti sputter layer 180a formed on one of the front surfaces or ribs 111 and 121 of the lower plate 110b or the upper plate 120b and a SnAg sputter layer formed on the Ti sputter layer 180a ( 180b). The multilayer structure of the Ti sputter layer 180a and the SnAg sputter layer 180b is a component that is brazed at a low temperature.

The SnAg sputter layer contains 95 to 98 wt% of Sn and 3 to 5 wt% of Ag. Preferably, the SnAg sputter layer consists of 97 wt% Sn and 3 wt% Ag.

The Ti sputter layer 180a may be formed to a thickness of 0.2 μm, and the SnAg sputter layer 180b may be formed to a thickness of 1 μm.

The thickness of each layer in the low-temperature bonding substrate 180 is designed in consideration of the coefficient of thermal expansion of each component. SnAg is a low melting point metal and has good wettability with copper.

For example, a Ti sputter layer 180a is formed on the front surface of the lower plate 110b or on the ribs 111 for surface modification after cleaning since the base material must be clean before brazing for good bonding.

The Ti sputter layer 180a forms an intermetallic compound (CuTi) with Cu, and increases adhesion to the SnAg sputter layer 180b. In the bonding of the SnAg sputter layer 180b and Cu, SnAg forms a Sn-Ag-Cu-based intermetallic compound to improve wettability and adhesion, thereby improving bonding properties.

As shown in FIG. 12 , the lower plate 110b has a structure in which ribs 111 are formed along the edge. The ribs 111 are integrally formed during injection molding of the lower plate 110b.

The upper plate 120b has a rib 121 formed along the edge, and a concave groove 123 is formed in a predetermined area along the longitudinal direction in the center, and first dots 125a on both sides of the concave groove 123 as a reference. ) and the second dot 125b having a smaller diameter than the first dot 125a have a structure in which they are intersected.

In the upper plate 120b, the rib 121, the concave groove 123, the first dots 125a, and the second dots 125b are integrally formed during injection molding of the upper plate 120b. The concave groove 123 is formed to be more concave than other portions of the upper plate 120b.

The upper wick 140b is fitted into the concave groove 123 of the upper plate 120b and the lower wick 130b is fixed to the surface of the lower plate 110b except for the ribs 121 .

The lower plate 110b and the upper plate 120b are joined by low-temperature brazing in a state in which the ribs 111 and 121 face each other through the low-temperature bonding substrate 180 .

In the sheet-type heat pipe 100b, the ribs 111 may be formed only on the edge of the lower plate 110b.

Hereinafter, a method of manufacturing the sheet-type heat pipe according to the third embodiment will be described.

As shown in FIGS. 10 and 11 , the method for manufacturing a sheet-type heat pipe includes the steps of forming a lower plate 110b having ribs 111 along the edge, and concave grooves 123 are formed along the longitudinal direction. Forming the upper plate 120b in which a plurality of dots 125 are formed on both sides of the inlet groove 123, disposing the lower wick 130b on the inner surface of the lower plate 110b, and the indentation groove of the upper plate 120b It includes the steps of disposing the upper wick 140b on the 123 and performing low-temperature brazing to seal and bond the edges of the lower plate 110b and the upper plate 120b.

The lower plate 110b and the upper plate 120b are formed of a polymer-based material having a low dielectric constant with improved thermal conductivity. Preferably, the upper plate 120b and the lower plate 110b are formed by mixing boron nitride as a ceramic filler with polypropylene (PP).

The lower wick 130b and the upper wick 140b are formed of a PVDF nanofiber membrane so that the pore size can be adjusted, and the surface is electroless-plated with copper or nickel to have electrical conductivity and thermal conductivity.

In the step of disposing the lower wick 130b on the inner surface of the lower plate 110b, a volatile adhesive 135 is disposed between the inner surface of the lower plate 110b and the lower wick 130b, and the volatile adhesive 135 is low-temperature brazing It is melted in the process of performing the lower wick 130b may be attached to the inner surface of the lower plate (110b). For example, the volatile adhesive 135 may be a ceramic bond that is volatilized at about 200°C.

In the step of forming the lower plate 110b in which the ribs 111 are formed along the edges, the ribs 111 are integrally formed during injection molding of the lower plate 110b.

In the step of forming the upper plate 120b in which the concave groove 123 is formed along the longitudinal direction and the dot 125 is formed on both sides of the concave groove 123, the concave groove 123 and the dot 125 are the upper plate 120b. ) is integrally formed during injection molding.

The step of performing low-temperature brazing to seal and bond the edges of the lower plate 110b and the upper plate 120b is to form the low-temperature bonding substrate 180 on the edge of the lower plate 110b or the upper plate 120b, or the lower plate 110b or A low-temperature bonding substrate 180 is formed on the entire surface of the upper plate 120b, and heat-bonded at a temperature of 200 to 300°C. Preferably, the low-temperature brazing is carried out at a temperature of 250°C.

The low-temperature bonding substrate 180 is a Ti sputter layer 180a formed by sputtering along the front surface or an edge of the lower plate 110b or the upper plate 120b, and SnAg formed by sputtering on the Ti sputter layer 180a. and a sputter layer 180b.

The sheet-like heat pipe 100b includes an inlet 170 .

After the low-temperature brazing step, the refrigerant 150 is injected into the inlet 170 and the inlet 170 is sealed. The refrigerant 150 is injected while removing the vacuum in the inner space 101 . The refrigerant 150 uses water having a high specific heat. The refrigerant 150 may be injected into the inner space 101 so as to contain about 10 to 20% by volume.

Hereinafter, the operation of the third embodiment will be described.

The sheet-shaped heat pipe 100b according to the third embodiment is manufactured by four parts: a lower plate 110b, an upper plate 120b, a lower wick 130b, and an upper wick 140b.

The sheet-type heat pipe 100b is formed by joining the edges of the lower plate 110b and the upper plate 120b to form an inner space 101 therebetween, and a lower wick 130b and an upper wick 140b in the inner space 101. , and has a structure in which the refrigerant 150 is vacuum sealed.

In addition, the lower plate 110b and the upper plate 120b are formed of a polymer-based material of low dielectric constant with increased thermal conductivity, and the lower wick 130b and the upper wick 140b use a membrane wick with an adjustable pore size, The refrigerant 150 uses water having a low specific heat.

In the above structure, the lower wick 130b can secure a space for the liquid to flow with high thermal conductivity by adjusting the pore size, thereby enabling rapid liquid diffusion, and the upper wick 140b has thermal conductivity and thermal conductivity by adjusting the pore size. Since a denser structure can be formed together, it is possible to quickly absorb steam and move quickly, so that the movement of the refrigerant through a phase change can be made wider and faster, thereby increasing the heat dissipation efficiency.

In addition, the sheet-shaped heat pipe 100b has a structure in which a plurality of dots 125 protruding toward the lower plate 110b and contacting the lower wick 130b are formed on the upper plate 120b. These dots 125 are disposed between the lower plate 110b and the upper plate 120b and serve as a support to prevent distortion of the inner space 101, so that the refrigerant moves more smoothly, thereby increasing the heat dissipation efficiency. .

In addition, the lower plate 110b and the upper plate 120b form ribs 111 and 121 on the edges to secure a space for the lower wick 130b and the upper wick 140b to be disposed therein, and the dots 125 on the upper plate 120b. ) is formed to prevent distortion of the inner space 101, and the ribs 111 and 121 and the dots 125 are integrally formed during injection molding of the lower plate 110b and the upper plate 120b, so the process can be simplified and ㎛ It is possible to manufacture the sheet-type heat pipe 100b having a thin thickness as a unit.

In addition, the edges of the lower plate 110b and the upper plate 120b are joined by low-temperature brazing via the low-temperature bonding substrate 180 .

Low-temperature brazing is possible by the low-temperature bonding substrate 180 including the Ti sputter layer 180a and the SnAg sputter layer 180b formed by sputtering on the Ti sputter layer 180a. Such a low-temperature bonding substrate 180 can seal and bond the lower plate 110b and the upper plate 120b, which are thin in μm units, and the polymer-based material, which are a polymer-based material, uniformly at a low temperature without a difference in height of the internal components, and thus the inner space 101 ), it is possible to quickly move the refrigerant 150 injected into it and prevent leakage, so that a sheet-type heat pipe with excellent heat dissipation performance can be manufactured.

[Fourth embodiment]

13 , the sheet-type heat pipe 100c according to the fourth embodiment includes a lower plate 110c, an upper plate 120c, a gasket 190, a wick 140c, and a refrigerant 150. do.

The lower plate 110c and the upper plate 120c are positioned to face each other, and the edges are sealed and bonded through the gasket 190 to form an inner space 101 between the inner surfaces facing each other. A wick 140c for inducing rapid liquid diffusion and rapid vapor movement is disposed in the inner space 101 , and a refrigerant 150 having heat transfer characteristics due to phase change is vacuum-sealed. The refrigerant 150 may be made of water.

The sheet-shaped heat pipe 100c includes an inlet 170 for injecting a refrigerant. The inlet 170 is sealed after the injection of the refrigerant. In the sheet-type heat pipe 100c, the inner space 101 is sealed with a vacuum, and a refrigerant is injected while the vacuum of the inner space 101 is removed. When the internal space 101 is vacuumed, the phase change of the refrigerant 150 proceeds at a temperature lower than atmospheric pressure, thereby increasing heat dissipation efficiency.

The refrigerant 150 may be contained in the internal space 101 by 10 to 20% by volume.

The lower plate 110c has one bottom surface in contact with the heat source, and the upper plate 120c is disposed on top of the lower plate 110c to overlap each other. One side of the gasket 190 is sealed with the rim of the lower plate 110c to form an inner space 101 between the lower plate 110c and the upper plate 120c, and the other surface of the gasket 190 is sealed with the rim of the upper plate 120c. are very joined The heat source may be an AP or an antenna chip.

The lower plate 110c and the upper plate 120c are formed in a flat plate shape.

The lower plate 110c and the upper plate 120c may be formed of a metal material. For example, the lower plate 110c and the upper plate 120c may be formed of copper (Cu) or a copper alloy having high thermal conductivity. When the lower plate 110c and the upper plate 120c are formed of a metal material, there are advantages in securing strength and securing thermal conductivity.

Alternatively, the lower plate 110c and the upper plate 120c may be formed of a polymer-based material.

A polymer-based material is one in which a low dielectric constant polymer is mixed with a ceramic filler to increase thermal conductivity. The ceramic filler may be boronnitride. The low dielectric constant polymer may be one of low dielectric constant polypropylene (PP) and polyethylene (PE). When the lower plate 110c and the upper plate 120c are formed of a polymer-based material, there is a cost reduction and ease of the manufacturing process.

The gasket 190 is for forming an inner space therebetween using the upper plate 120c and the lower plate 110c of a flat plate shape. In the fourth embodiment, the inner space 101 is formed between the lower plate 110c and the upper plate 120c using the gasket 190 .

Since the gasket 190 joins the edges of the upper plate 120c and the lower plate 110c, the gasket 190 may be formed in a shape corresponding to the edges of the upper plate 120c and the lower plate 110c. For example, as shown in FIG. 14A , the gasket 190 may be formed in a square shape with an empty center.

Alternatively, as shown in FIGS. 14B and 14C , the gasket 190 may be formed in a shape in which the reinforcing parts 191 are formed at regular intervals in an empty space of a rectangular shape. The reinforcing part 191 secures the inner space 101 between the lower plate 110c and the upper plate 120c instead of the dots described in the first to fourth embodiments and prevents the inner space 101 from being crushed. play a role

The structure of the gasket 190 having the reinforcing part 191 provides an internal space 101 sufficient to enclose the refrigerant 150 and increases rigidity to prevent the internal space 101 from being crushed due to a pressure difference from atmospheric pressure. And, it is possible to increase the heat dissipation efficiency by providing a wider flow path through which the refrigerant 150 moves.

The gasket 190 may be formed of a metal material. Alternatively, the gasket 190 may be formed of a polymer-based material. For example, the gasket 190 may be formed of copper (Cu) or a copper alloy having high thermal conductivity, or may be formed of a polymer-based material having a high thermal conductivity by mixing a low dielectric constant polymer with a ceramic filler.

As shown in FIG. 13 , a wick 140c is disposed inside the gasket 190 . To this end, the gasket 190 may be formed with a step for supporting the wick 140c.

The wick 140c may include a nonwoven fabric 141 and membrane wicks 142 and 143 disposed above and below the nonwoven fabric 141 . The nonwoven fabric 141 may be formed of nanofibers. The nonwoven fabric 141 may be formed by electroless plating on the nanofiber to increase thermal conductivity.

The membrane wicks 142 and 143 disposed on the upper and lower portions of the nonwoven fabric 141 may be formed by electroless plating on a polyvinylidene fluoride (PVDF) nanofiber membrane. Electroless plating can be performed with a metal having excellent thermal conductivity, such as copper or nickel. In addition to the electroless plating, at least one of aluminum, silver, titanium, chromium, gold, carbon, iron, platinum, and graphite or an alloy of two or more thereof may be used.

The PVDF nanofiber membrane has a thin and uniform pore distribution with a fiber thickness of 0.2 to 0.3 μm. When the membrane wicks 142 and 143 are formed by plating copper or nickel on the surface of the PVDF nanofiber membrane, the pore size can be adjusted while having the same thermal conductivity as metal, so that the movement speed of the refrigerant can be faster. .

The membrane wick 142 disposed under the nonwoven fabric 141 and the membrane wick 143 disposed on the top of the nonwoven fabric 141 adjust the pore size to enable rapid diffusion of liquid and rapid movement and diffusion of vapor. can

For example, the pores of the membrane wick 142 disposed under the nonwoven fabric 141 may be made larger than the pores of the membrane wick 143 disposed above the nonwoven fabric 141 .

The membrane wick 142 disposed under the nonwoven fabric 141 has a large pore size to provide a space for the liquid to move, and the membrane wick 143 disposed on the top of the nonwoven fabric 141 minimizes pores. By forming a compact structure, it can be manufactured to enable rapid movement of steam through rapid absorption of steam.

Membrane wicks 142 and 143 cause capillary action so that the vapor moves quickly and spreads widely, so that cooling occurs quickly.

In the fourth embodiment, the gasket 190 and the wick 140c form the inner space 101 between the lower plate 110c and the upper plate 120c and serve as a support to prevent distortion.

Furthermore, since the membrane wicks 142 and 143 are formed by plating copper or nickel on the surface of the PVDF nanofiber membrane, they are manufactured in a structure that accelerates moisture absorption through pore size control, thereby inducing more rapid moisture absorption and movement to improve heat dissipation performance. can be raised

As shown in FIG. 14A , the gasket 190 may be formed in a rectangular shape with an empty center.

Alternatively, as shown in FIGS. 14B and 14C , the gaskets 190 ′ and 190 ″ may be formed in a shape in which the reinforcing parts 191 are formed at regular intervals in an empty space of a rectangular shape.

As shown in FIG. 14B, the reinforcing part 191 has one end fixed to a square-shaped rim located opposite the inlet 170, and the opposite end consists of two or more straight reinforcing ribs positioned to be spaced apart from the inlet 170. can be

Alternatively, as shown in FIG. 14C , the reinforcing portion 191 has one end fixed to a square-shaped rim located opposite the inlet 170 and the opposite end is spaced apart from the inlet 170. One or more reinforcing One or more reinforcing ribs (191b), one end of which is fixed to the square-shaped rim adjacent to the inlet 170 and the other end of which is spaced apart from the square-shaped rim located on the opposite side of the inlet (170). can The two types of reinforcing meat 191a and 191b form a zigzag flow path in the width direction to serve as a support for preventing the inner space 101 from being crushed without affecting the longitudinal movement of the refrigerant.

When the reinforcing part 191 is formed in the gasket 190 , the wick 140c may be disposed in a space between the reinforcing ribs 191a and 191b.

The refrigerant 150 may be included in the internal space 101 in terms of volume ratio of about 10 to 20% in consideration of an increase in the volume of vapor according to the phase change.

The lower plate 110c and the upper plate 120c are joined at a low temperature using the low-temperature bonding substrate 180 in a state where the edges are abutted with the gasket 190 interposed therebetween.

The low-temperature bonding substrate 180 seals one surface of the gasket 190 to the lower plate 110c and seals the other surface to the upper plate 120c.

The low-temperature bonding substrate 180 may be formed on the entire surface of the lower plate 110c and the upper plate 120c or on the other surface opposite to one surface of the gasket 190 .

When the low-temperature bonding substrate 180 is formed on the entire surface of the lower plate 110c and the upper plate 120c, the edges of the lower plate 110c and the upper plate 120c are bonded to one side and the other side of the gasket 190, respectively, in the low-temperature bonding process. At the same time, the upper membrane wick 143 of the nonwoven fabric 141 is bonded to the inner surface of the upper plate 120c, and the membrane wick 142 in the lower portion of the nonwoven fabric 141 is bonded to the inner surface of the lower plate 110c. can

In the embodiment, the low-temperature bonding substrate 180 is formed by sputtering on the other surface opposite to one surface of the gasket 190 . The reason is that since the gasket 190 supports the wick 140c, it is not necessary to form the low-temperature bonding substrate 180 on the front surfaces of the lower plate 110c and the upper plate 120c.

The low-temperature bonding substrate 180 is melted at a temperature of 200 to 300° C. to bond the edges of the lower plate 110c and the upper plate 120c to one surface and the other surface of the gasket 190 . Preferably, the lower plate 110c and the upper plate 120c are heated at 250° C., which is the brazing temperature of the low-temperature bonding substrate 180, in a state in which the gasket 190 is interposed therebetween, thereby bonding the edges to the gasket 190.

The low-temperature bonding is to enable the wick 140c to be applied to the structure of the non-metallic nonwoven fabric 141 and the membrane wicks 142 and 143 . When the wick 140c is manufactured with the structure of the nonwoven fabric 141 and the membrane wicks 142 and 143, it has the advantage that the support role and the pore size can be adjusted to a desired size. will lose Therefore, only when low-temperature bonding is possible, the wick 140c can be applied to the structure of the nonwoven fabric 141 and the membrane wicks 142 and 143 in which the support function and the pore size can be adjusted.

The low-temperature bonding substrate 180 is formed of a sputtered thin film having a multi-layer structure. The multi-layered thin film is intended to enhance the bonding strength by complementing the insufficient performance.

The low-temperature bonding substrate 180 is a Ti sputter layer 180a and a Ti sputter layer 180a formed on the front surface of the lower plate 110c and the upper plate 120c, or on one and the other surfaces of the gasket 190, SnAg sputter formed on the top. layer 180b. The multilayer structure of the Ti sputter layer 180a and the SnAg sputter layer 180b is a component that is brazed at a low temperature.

The SnAg sputter layer contains 95 to 98 wt% of Sn and 3 to 5 wt% of Ag. Preferably, the SnAg sputter layer consists of 97 wt% Sn and 3 wt% Ag.

The Ti sputter layer 180a may be formed to a thickness of 0.2 μm, and the SnAg sputter layer 180b may be formed to a thickness of 1 μm.

The thickness of each layer in the low-temperature bonding substrate 180 is designed in consideration of the coefficient of thermal expansion of each component, and when the thickness of each layer is designed, the bonding strength between the lower plate 110c and the upper plate 120c is increased. SnAg is a low melting point metal and has good wettability with copper.

For example, the Ti sputter layer 180a is formed on the ribs 111 of the lower plate 110c for surface modification after washing because the base material must be clean before brazing for good bonding.

The Ti sputtered layer 180a forms an intermetallic compound (CuTi) with Cu, and adhesion to the SnAg sputtered layer 180b is increased. In the bonding of the SnAg sputter layer 180b and Cu, SnAg forms a Sn-Ag-Cu-based intermetallic compound to improve wettability and adhesion, thereby improving bonding properties.

Hereinafter, a method of manufacturing the sheet-type heat pipe according to the fourth embodiment will be described.

The manufacturing method of the sheet-type heat pipe includes the steps of preparing a lower plate 110c and an upper plate 120c having the same size and formed in a flat plate shape, and a lower plate 110c to form an internal space between the lower plate 110c and the upper plate 120c. ) and arranging the gasket 190 on the edge between the upper plate 120c, and performing low-temperature brazing so that the lower plate and the upper plate 120c are sealed and bonded through the gasket 190.

The lower plate 110c and the upper plate 120c may be formed of copper (Cu) or a copper alloy having high thermal conductivity. Alternatively, the lower plate 110c and the upper plate 120c may be formed of a polymer-based material. The gasket 190 may be formed of copper (Cu) or a copper alloy having high thermal conductivity. Alternatively, the gasket 190 may be formed of a polymer-based material.

The polymer-based material may be one in which a low dielectric constant polymer is mixed with boron nitride to increase thermal conductivity. The low dielectric constant polymer may be one of low dielectric constant polypropylene (PP) and polyethylene (PE).

Low-temperature brazing can be performed at 200-300°C.

For low-temperature brazing, a low-temperature bonding substrate 180 formed on the front surface of the lower plate 110c and the upper plate 120c or on the other surface opposite to one surface of the gasket 190 is included.

In the embodiment, the low-temperature bonding substrate 180 is formed on the entire surface of the lower plate 110c and the upper plate 120c, and heat-bonded at a temperature of 200 to 300°C. Preferably, the low-temperature brazing is carried out at a temperature of 250°C.

The low-temperature bonding substrate 180 is a Ti sputter layer 180a formed by sputtering on the entire surface of the lower plate 110c and the upper plate 120c and a SnAg sputter layer 180b formed by sputtering on the Ti sputter layer 180a by sputtering. ) is included.

After performing the low-temperature brazing, the refrigerant 150 is injected into the inlet 170 and the inlet 170 is sealed. The refrigerant 150 is injected while removing the vacuum in the inner space 101 . The refrigerant 150 may use water. The refrigerant 150 may be injected into the inner space 101 so as to contain about 10 to 20% by volume.

Hereinafter, the operation of the fourth embodiment will be described.

The sheet-shaped heat pipe 100c according to the fourth embodiment is manufactured by four parts: a lower plate 110c, an upper plate 120c, a gasket 190, and a wick 140c.

The sheet-type heat pipe 100c is formed by bonding the edges of the lower plate 110c and the upper plate 120c through a gasket 190 to form an internal space 101 therebetween, and a wick 140c to the gasket 190. It has a structure in which the refrigerant 150 is vacuum sealed.

The wick 140c applies membrane wicks 142 and 143 with adjustable pore sizes to the upper and lower portions of the nonwoven fabric 141 , and the refrigerant 150 uses water.

In the above structure, the gasket 190 and the wick 140c secure the inner space 101 through which the refrigerant can move between the lower plate 110c and the upper plate 120c and prevent the inner space 101 from being crushed. serves as a support.

In addition, the membrane wick 142 disposed under the nonwoven fabric 141 can secure a space for the liquid to flow with high thermal conductivity, thereby enabling rapid liquid diffusion, and the membrane wick 143 disposed on the top of the nonwoven fabric 141 . ) has a denser structure with thermal conductivity and absorbs steam quickly and moves quickly, so it can increase the heat dissipation efficiency by making the refrigerant move wider and faster through phase change.

In addition, since the gasket 190 secures a space for the wick 140c to be disposed between the lower plate 110c and the upper plate 120c, there is no need to form a grooved structure in the lower plate 110c and the upper plate 120c. No, it can be used in a flat plate shape. Due to this, it is possible to simplify the process and to manufacture the sheet-type heat pipe 100c having a thin thickness in the unit of μm.

In addition, in the sheet-type heat pipe 100c, the edges of the lower plate 110c and the upper plate 120c are joined to the gasket 190 by low-temperature brazing via the low-temperature bonding substrate 180 .

Low-temperature brazing is possible by the low-temperature bonding substrate 180 including the Ti sputter layer 180a and the SnAg sputter layer 180b formed by sputtering on the Ti sputter layer 180a. This low-temperature bonding substrate 180 can seal and bond the lower plate 110c and the upper plate 120c, which are thin in μm in units of μm, uniformly without a difference in height of the internal components at low temperatures, and thus the inner space 101 is injected into the It is possible to quickly move the refrigerant 150 and prevent leakage, so that a sheet-type heat pipe having excellent heat dissipation performance can be manufactured.

[Example 5]

15 , the sheet-type heat pipe 100d according to the fifth embodiment includes a lower plate 110c, an upper plate 120c, a gasket 190, a wick 140c, and a refrigerant 150. do.

The sheet-type heat pipe 100d according to the fifth embodiment is different from the fourth embodiment in that the hydrophobic coating layer 127 is formed on the inner surfaces of the lower plate 110c and the upper plate 120c.

The hydrophobic coating layer 127 allows the condensed refrigerant to fall and spread well to facilitate the movement of the refrigerant. In addition, the hydrophobic coating layer 127 coated on the inner surface of the lower plate 110c serves to lubricate the refrigerant to flow well. When the refrigerant is condensed, the refrigerant must be well separated from the upper plate 120c to facilitate circulation through the phase change of the refrigerant.

The hydrophobic coating layer 127 may be made of chromium nitride (CrN). Chromium nitride is resistant to high temperatures and has excellent hydrophobic properties.

The thickness of the hydrophobic coating layer 127 may be in the range of 1 to 5 μm. The hydrophobic coating layer 127 may be formed on the inner surfaces of the lower plate 110c and the upper plate 120c by sputtering.

Although the hydrophobic coating layer 127 of the fifth embodiment has been described using the structure of the fourth embodiment, it is also applicable to the lower plate 110c and the upper plate 120c of the first to third embodiments.

Although the above-described embodiments have been described as an example of attaching the sheet-type heat pipe to the application processor (AP) of the smartphone, it is applicable to various electronic devices requiring heat dissipation. In particular, the sheet-type heat pipe can be applied to antennas that may generate heat due to the commercialization of 5G.

In addition, in the above-described first to fifth embodiments, a sheet-type heat pipe may be manufactured by combining the configurations of each embodiment under applicable conditions.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is disclosed in the drawings and in the specification with preferred embodiments. Here, although specific terms have been used, they are only used for the purpose of describing the present invention and are not used to limit the meaning or the scope of the present invention described in the claims. Therefore, it will be understood by those skilled in the art that various modifications and equivalent other embodiments of the present invention are possible therefrom. Accordingly, the true technical scope of the present invention should be defined by the technical spirit of the appended claims.

1: Smartphone 10: Application Processor (AP)
100: sheet-type heat pipe 101: internal space
110,110a,110b,110c: lower plate 111: rib
120, 120a, 120b, 120c: top plate 123: concave groove
125: dot 125a: first dot
125b: second dot 127: hydrophobic coating layer
130: woven mesh 135: volatile adhesive
140, 140a: wick 150: refrigerant
160: high-temperature bonding material 170: inlet
180: low-temperature bonding material 190: gasket
191: reinforcement part

Claims (19)

a lower plate in contact with a heat source on the bottom;
an upper plate that is sealedly joined to the rim of the lower plate to form an inner space therebetween;
Woven mesh disposed in the longitudinal direction on the inner surface of the lower plate (Woven Mesh);
a wick disposed on the inner surface of the upper plate; and
a refrigerant sealed in a vacuum in the inner space and having heat transfer characteristics due to phase change;
including,
The upper plate is a sheet-type heat pipe having a plurality of dots protruding toward the lower plate on both sides where the wick is disposed and in contact with the woven mesh. The method of claim 1,
A sheet-type heat pipe spaced apart between the wick and the woven mesh. The method of claim 1,
A sheet-type heat pipe in which the upper plate is provided with a concave groove concave in the longitudinal direction on an inner surface, and the wick is inserted into the concave groove. delete The method of claim 1,
The dot is a sheet-type heat pipe in which a first dot and a second dot having a smaller diameter than the first dot are intersected. The method of claim 1,
It includes a high-temperature bonding substrate for bonding the edges of the lower plate and the upper plate,
The high-temperature bonding substrate may include a Ti sputter layer formed along the front or edge of the lower or upper plate;
a Cu sputter layer formed on the Ti sputter layer;
an Ag plating layer formed on the Cu sputter layer;
a Cu plating layer formed on the Ag plating layer; and
an Ag plating layer formed on the Cu plating layer;
A sheet-type heat pipe comprising a. forming a lower plate in which ribs are formed along the edge;
Forming an upper plate in which a concave groove is formed along the longitudinal direction and a plurality of dots are formed on both sides of the concave groove;
disposing a woven mesh on the inner surface of the lower plate;
disposing a wick in the concave groove of the upper plate; and
Comprising the step of performing high-temperature brazing so as to seal the edges of the lower plate and the upper plate,
In the step of forming an upper plate in which a concave groove is formed along the longitudinal direction and a plurality of dots are formed on both sides of the concave groove,
The plurality of dots are formed by etching the upper plate. 8. The method of claim 7,
including an entrance,
After the high-temperature brazing step, a refrigerant is injected into the inlet and the inlet is sealed. 8. The method of claim 7,
In the step of disposing a woven mesh on the inner surface of the lower plate,
A volatile adhesive is disposed between the inner surface of the lower plate and the woven mesh,
The volatile adhesive is melted during the high-temperature brazing process to attach the woven mesh to the inner surface of the lower plate. 8. The method of claim 7,
In the step of performing high-temperature brazing so as to seal and bond the edges of the lower plate and the upper plate, a high-temperature bonding substrate is disposed on the edge of the lower plate or the upper plate, and a sheet-type heat pipe manufacturing method of heat-bonding at 900 to 1000°C. delete delete delete delete delete delete delete delete delete

Images