TWI497025B - Flat heat pipe and method for manufacturing the same - Google Patents

Description

Flat heat pipe and method of manufacturing same

The present invention relates to a heat pipe, and more particularly to a flat heat pipe applied to the field of heat dissipation of electronic components and a method of manufacturing the same.

At this stage, the heat pipe has been widely used in electronic components with large heat generation because of its high heat transfer capacity. When the heat pipe is in operation, the low-boiling working medium filled inside the pipe body absorbs the heat generated by the heat-generating electronic component in the evaporation portion, and then evaporates and vaporizes, the vapor moves with heat to the condensation portion, and condenses and condenses in the condensation portion to release the heat. Thereby dissipating heat from the electronic components. The liquefied working medium is returned to the evaporation portion under the action of the capillary structure of the heat pipe wall, and further evaporative vaporization and liquefaction condensation are performed, so that the working medium moves back inside the heat pipe, and the heat generated by the electronic component is continuously emitted. .

The capillary structure of the conventional heat pipe can be generally divided into a groove type, a sintered type, a fiber type and a wire mesh type, and the characteristics of the capillary structure are single, and the permeability of the groove type, the fiber type, and the wire mesh type capillary structure is high. The thermal resistance is small, but its capillary force is weak, and the maximum heat transfer loss after flattening is large; the sintered capillary structure has strong capillary force and good anti-gravity effect, and the maximum heat loss after flattening is small, but its permeability is low. The thermal resistance is large.

In view of this, it is necessary to provide a flat heat pipe for improving the performance of the heat pipe and its manufacture. method.

A flat heat pipe comprises a hollow flat tube body and a first capillary structure and a second capillary structure disposed in the tube body, wherein the second capillary structure is a sintered structure formed by sintering a metal powder, and the first capillary structure is The first capillary structure and the second capillary structure are in contact with each other, and the tube body is in the first capillary structure, and is a groove-like structure formed by a plurality of spaced protrusions and a groove formed between the adjacent protrusions. A vapor passage is formed with a region other than the second capillary structure.

A method for manufacturing a flat heat pipe includes the steps of: providing a rod body having a cylindrical shape, an opening and a notch formed on an outer circumferential surface thereof; and providing a round tube, the round tube being hollow, including an arc a first portion of the shape and an arcuate second portion connected to the first portion, an arcuate rib at the inner top end of the first portion projecting toward the center of the circular tube, the length of the first portion in the circumferential direction being much smaller than the second portion The circumferential length, the inner diameter of the second portion is equivalent to the outer diameter of the rod body, the rod body is inserted into the round tube, and the rib of the first portion of the round tube is received in the opening; the metal powder is filled in the location In the notch of the rod body in the circular tube, the metal powder is sintered at a high temperature to form a second capillary structure; the rod body is taken out, and the ribs of the first portion of the circular tube are etched to form a plurality of spaced protrusions and adjacent protrusions Forming a groove therebetween, the protrusions and the grooves together form a first capillary structure, the first and second capillary structures are left on the inner wall of the circular tube; and the round tube is flattened to form a flat heat pipe, Making the second capillary structure Bonded to the first capillary structure, in the flat in the first capillary and the second capillary structure within the heat pipe The area outside the structure forms a vapor channel.

In the above flat heat pipe and the method of manufacturing the same, the first capillary structure is disposed on one side of the tube body, and the second capillary structure is disposed on the other side of the tube body, and the first, The second capillary structure is in contact with each other. When the heat pipe is in operation, the working medium can penetrate each other between the first and second capillary structures, and has a large capillary force, a high permeability and a relatively high permeability. Small heat resistance, so that the heat pipe has good heat transfer performance.

10, 20, 30, 40‧‧‧ flat heat pipes

11‧‧‧Body

12, 22, 32, 42, 17‧‧‧ first capillary structure

13, 23, 33, 43, 18, 18a‧‧‧Second capillary structure

14, 14a‧‧‧ rod body

16‧‧‧ round tube

19, 19a‧‧‧ Round heat pipe

101‧‧‧Evaporation section

102‧‧‧Condensation section

110‧‧‧Internal space

111‧‧‧ top board

112‧‧‧floor

113, 114‧‧‧ side panels

118‧‧‧Vapor passage

141‧‧‧ openings

142, 142a‧‧ ‧ gap

121,221,321,421,1651‧‧‧ bumps

123, 1653‧‧‧ trench

161‧‧‧Part 1

163‧‧‧Part II

165‧‧ ‧ ribs

181‧‧‧ Straight side

182‧‧‧Arc edge

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevational view of a flat heat pipe according to a first embodiment of the present invention.

2 is a schematic transverse cross-sectional view of the flat heat pipe of FIG. 1 taken along line II-II.

3 is a flow chart of a method of manufacturing the flat heat pipe shown in FIG. 1.

4 is a schematic perspective view of a rod body and a round tube in the manufacturing method shown in FIG. 3.

Fig. 5 is a schematic transverse cross-sectional view of the rod body taken along line V-V in the manufacturing method shown in Fig. 4.

Figure 6 is a schematic transverse cross-sectional view of a circular heat pipe in the manufacturing method of Figure 3.

Figure 7 is a transverse cross-sectional view showing a flat heat pipe according to a second embodiment of the present invention.

Figure 8 is a transverse cross-sectional view showing a flat heat pipe according to a third embodiment of the present invention.

Figure 9 is a schematic transverse cross-sectional view of a circular heat pipe in the manufacturing method of Figure 8.

Fig. 10 is a schematic transverse cross-sectional view showing a rod body in another manufacturing method of the flat heat pipe shown in Fig. 9.

Figure 11 is a transverse cross-sectional view showing a flat heat pipe according to a fourth embodiment of the present invention.

1 and 2 show a flat heat pipe 10 according to a first embodiment of the present invention. The heat pipe 10 includes an elongated flat tube body 11 and a first capillary structure 12 longitudinally disposed in the tube body 11. And a second capillary structure 13, and an appropriate amount of working medium (not shown) injected into the tube body 11. The heat pipe 10 has an evaporation section 101 and a condensation section 102 along the length direction. The evaporation section 101 and the condensation section 102 are respectively disposed at two ends of the tube body 11.

The tube body 11 is made of a material having good thermal conductivity such as copper, which can transfer external heat to the inside. The tube body 11 has a hollow seal shape, and an inner space 110 is formed therein. The tube body 11 is formed by flattening a hollow tube. The tube body 11 includes a top plate 111, a bottom plate 112 and two side plates 113, 114. The top plate 111 and the bottom plate 112 are parallel to each other and are vertically opposed to each other. The two side plates 113 and 114 are arc-shaped, and are respectively located at two sides of the pipe body 11 and connected to the top plate 111 and the bottom plate 112, so that the pipe body 11 is in contact with A longitudinally vertical cross section forms a runway-like profile.

The first capillary structure 12 has a continuous groove shape and includes a plurality of equally spaced protrusions 121 and a groove 123 formed between the two adjacent protrusions. These projections 121 are provided on the central side in the tubular body 11. In this embodiment, the protrusion 121 of the first capillary structure 12 is a trapezoid having a cross section that is slightly smaller and smaller, and is formed to protrude upward from the middle of the inner surface of the bottom plate 112 of the tube body 11, and the top end thereof is flush and coupled. On the second capillary structure 13. The first capillary structure 12 has a large void ratio, so that the permeability is high and the thermal resistance is small, which is beneficial to the smooth flow of the working medium in the groove 123 thereof.

The second capillary structure 13 is different from the first capillary structure 12 in that it is a porous structure formed by sintering a metal powder such as copper. The second capillary structure 13 has small internal voids, large evaporation surface area, strong capillary force, good anti-gravity effect, and small loss of maximum heat transfer after flattening, which contributes to evaporation and heat absorption of the working medium, thereby effectively transmitting the heat pipe. The heat of the evaporation section 101 of 10. The second capillary structure 13 is disposed in the tube body 11 The other side of the middle portion facing the first capillary structure 12, that is, the second capillary structure 13 is facing the first capillary structure 12. The size of the second capillary structure 13 attached to one side of the first capillary structure 12 is smaller than the size of the side of the second capillary structure 13 away from the first capillary structure 12. In the present embodiment, the second capillary structure 13 has a substantially triangular prism shape, and the top end surface of the larger size is closely adhered to the inner surface of the top plate 111 of the tube body 11 by high temperature sintering, and the larger size bottom is formed. The end forms a tip and is fitted to and partially embedded in the projection 121 of the central portion of the first capillary structure 12.

The first and second capillary structures 12 and 13 are laminated on top of each other, and the internal space 110 of the tubular body 11 is divided into two in the longitudinal direction, so as to be on both sides of the first and second capillary structures 12 and 13 A vapor passage 118 is formed which allows vapor to pass therethrough.

The working medium is a substance having a lower boiling point such as water, wax, alcohol or methanol. When the evaporation section 101 of the heat pipe 10 is in contact with a heat source (not shown), the working medium absorbs heat from the evaporation section 101 to evaporate, and moves to the condensation section 102 through the vapor passage 118, and condenses after the condensation section 102 releases heat. The liquid releases the heat and completes the heat dissipation from the heat source. The first and second capillary structures 12, 13 provide a capillary force to return the working medium formed by the condensation of the condensation section 102 of the pipe body 11 to the evaporation section 101, thereby realizing the loop motion of the working medium in the pipe body 11 to complete the pair. The heat source continues to dissipate heat.

In the heat pipe 10, the first capillary structure 12 has a groove shape, and is disposed on one side of the tube body 11 (the inner surface of the bottom plate 112), and the second capillary structure 13 is formed by sintering metal powder. It is disposed on the other side of the tube body 11 (the inner surface of the top plate 111), and the first and second capillary structures 12, 13 are located in the middle of the tube body 11 and are laminated on each other. When the heat pipe 10 is in operation, the working medium penetrates between the first and second capillary structures 12, 13 due to the sintered second capillary structure. 13 has a large capillary force, and has a high permeability and a small heat resistance due to the groove-shaped first capillary structure 12, so that the heat pipe 10 has good heat transfer performance. The thickness of the heat pipe 10 described above can be less than 2 mm, and even when the thickness of the heat pipe 10 is 1.5 mm, the heat pipe 10 can ensure good performance, and is suitable for electronic devices such as notebook computers having a small internal space.

The heat transfer performance of the heat pipe 10 of the present invention is higher than that of the conventional heat pipe by the specific experimental data. The following tests are carried out under the same conditions. The specifications and parameters of the heat pipes in the same table are the same. Among them, Q _max is the maximum heat transfer capacity of the heat pipe operating temperature at 50 ° C, and the average thermal resistance value R _th = (evaporation section) Average temperature (condensation section average temperature) / Q _max .

As shown in Table 1, in the case of being flattened to the same specification (thickness T = 2.0 mm), the average maximum heat transfer amount of the heat pipe 10 of the present invention is increased by about 24.5% compared with the conventional sintered heat pipe, and the average heat is simultaneously The resistance value is reduced by about 14.6% compared with the conventional sintered heat pipe. Therefore, the maximum heat transfer loss of the heat pipe 10 of the present invention after being flattened is small, the average thermal resistance value is also small, and the comprehensive performance is remarkably improved.

Table 2 Specifications are diameter (=6mm, length L=200mm, thickness T=1.5mm

As shown in Table 2, in the case of being flattened to the same specification (thickness T = 1.5 mm), the average maximum heat transfer amount of the heat pipe 10 of the present invention is increased by about 62.2% compared with the conventional sintered heat pipe, while the average heat The resistance value is reduced by about 34.8% compared with the conventional sintered heat pipe. Therefore, the maximum heat transfer loss of the heat pipe 10 of the present invention after being flattened is small, the average thermal resistance value is also small, and the comprehensive performance is remarkably improved.

3 to 6 show a manufacturing method of the heat pipe 10, which includes the following steps: providing a rod body 14, as shown in Figs. 4 and 5, the rod body 14 has a cylindrical shape on the outer circumferential surface thereof. The bottom portion of the rod body 14 is circumferentially opened with an arcuate opening 141. The top portion of the rod body 14 on the outer circumferential surface is directly cut off a small portion at the opening 141 so as to be on the outer circumferential surface of the rod body 14. A flat notch 142 is formed at the top, and the notch 142 is not in communication with the opening 141; a hollow metal tube 16 is provided, which can be divided into an arc-shaped first portion 161 and an arc-shaped portion connected to the first portion 161. Two parts 163. The first portion 161 and the second portion 163 have a uniform wall thickness, and the thickness of the first portion 161 is greater than the thickness of the second portion 163, that is, an arcuate rib 165 located at the inner top end of the first portion 161 is opposite to the second portion 163. The surface projects toward the center of the circular tube 16. The length of the first portion 161 in the circumferential direction is much smaller than the length of the second portion 163 in the circumferential direction. The inner diameter of the second portion 163 The outer diameter of the rod 14 is equivalent. Inserting the rod 14 into the circular tube 16 and accommodating the rib 165 of the first portion 161 of the circular tube 16 in the opening 141; providing a plurality of metal powders, as shown in Fig. 6, filling the metal powder in the round tube In the notch 142 of the rod 14 in the 16th, when the metal powder is filled, the metal powder having a fine particle diameter may be first filled, and then the metal powder having a relatively large particle diameter is gradually filled, and the round tube 16 is vibrated to cause the metal powder to be The gravity factor is distributed along the longitudinal direction of the circular tube 16 according to the particle size. After filling, the metal powder is sintered at a high temperature to form a second capillary structure 18. The cross-sectional mask of the second capillary structure 18 has a straight edge 181 and the straight edge. 181 is connected to a curved edge 182, wherein the curved edge 182 is adhered to the inner surface of the circular tube 16; the rod body 14 is taken out, and the ridge 165 of the first portion 161 of the circular tube 16 is etched to form a plurality of spaced and horizontal A protrusion 1651 having a trapezoidal shape with a small upper and lower cross section is formed, and a groove 1653 is formed between the adjacent two protrusions 1651. These protrusions 1651 and grooves 1653 together form a first capillary structure 17. The first and second capillary structures 17, 18 are left in the circular tube 16, and the first and second capillary structures 17, 18 are disposed opposite to each other and are respectively attached to a part of the inner wall of the circular tube 16; The circular tube 16 is filled with a working medium, vacuumed and closed to the longitudinal ends of the circular tube 16 to form a circular heat pipe 19; the first and second capillary structures 17, 18 are directly aligned to round the circular heat pipe 19, the heat pipe 10 of the first embodiment is formed, wherein the round pipe 16 is flattened to form a flat pipe body 11, and the first capillary structure 17 is flattened to form the first capillary structure 12 of the heat pipe 10, After the second capillary structure 18 is flattened, a second capillary structure 13 having a substantially triangular prism shape is formed, and a side of the second capillary structure 13 having a smaller size, that is, a bottom side is attached to the top surface of the first capillary structure 12. And a portion of the protrusion 121 in the middle of the first capillary structure 12 is embedded in the second capillary structure 13.

In the above manufacturing method, the notch 142 of the rod body 14 is straight, which can be directly milled out by a milling machine, and has low cost and is convenient for mass production.

Figure 7 shows a heat pipe 20 in a second embodiment of the present invention, which is similar to the heat pipe 10 of the first embodiment, except that the first capillary structure 22 is provided in the pipe body. In the middle left position of the second capillary structure 23, the second capillary structure 23 is disposed at a right-right position in the tubular body 11 and obliquely aligned with the first capillary structure 22, and the convex portion at the right end of the first capillary structure 22 The portion 221 is partially embedded in the top end of the second capillary structure 23 such that the protrusion 221 of the first capillary structure 22 not joined to the second capillary structure 23 is spaced apart from the left side of the second capillary structure 23. It can be understood that the protrusion 221 at the left end of the first capillary structure 22 can be partially embedded in the top end of the second capillary structure 23, so that the protrusion of the first capillary structure 22 not combined with the second capillary structure 23 is located at the second capillary. The right side of structure 23.

When manufacturing the heat pipe 20, it is only necessary to align the first capillary structure 17 and the second capillary structure 18 in Fig. 6 obliquely to round the circular heat pipe 19.

Figure 8 is a view showing a heat pipe 30 according to a third embodiment of the present invention, which is similar to the heat pipe 10 of the first embodiment, except that the second capillary structure 33 has a rectangular parallelepiped shape, The top surface is closely attached to the inner surface of the top plate 111 of the tube body 11, and the center of the bottom surface is attached to the top surface of the protrusion 321 of the first capillary structure 32.

9 and 10 show a method of manufacturing the heat pipe 30 described above, which is similar to the method of manufacturing the heat pipe 10 shown in Figs. 3 to 6, except that the notch 142a of the top of the rod 14a is The cross section is curved, and the cross section of the corresponding second capillary structure 18a formed in the circular heat pipe 19a is also curved. The second capillary structure 18a is flattened to form a second capillary structure 33 having a substantially rectangular parallelepiped shape.

Figure 11 is a view showing a heat pipe 40 in a fourth embodiment of the present invention, which is similar to the heat pipe 30 in the third embodiment, except that the first capillary structure 42 is provided in the pipe body. The second capillary structure 43 is obliquely aligned with the first capillary structure 42 in the left portion of the middle portion of the inner surface of the tube 11. The second capillary structure 43 is not closely attached to the left side of the bottom surface of the tube body 11 to which the top plate 111 is attached. The top surface of the protrusion 421 on the right side of the first capillary structure 42 is fitted. Of course, the first capillary structure 42 can also be disposed at a right position in the middle of the tube body 11. The second capillary structure 43 is not closely attached to the right side of the bottom surface of the tube body 11 to which the top plate 111 is attached. The top surface of the protrusion 421 on the left side of the first capillary structure 42.

When the heat pipe 40 is manufactured, it is only necessary to align the first capillary structure 17 and the second capillary structure 18a in Fig. 9 obliquely to the circular heat pipe 19a.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

10‧‧‧flat heat pipe

11‧‧‧Body

12‧‧‧First capillary structure

13‧‧‧Second capillary structure

110‧‧‧Internal space

111‧‧‧ top board

112‧‧‧floor

113, 114‧‧‧ side panels

118‧‧‧Vapor passage

121‧‧‧ bumps

123‧‧‧ trench

Claims (14)

A flat heat pipe comprising a hollow flat tube body and a first capillary structure and a second capillary structure disposed in the tube body, wherein the second capillary structure is a sintered structure formed by sintering a metal powder, the first a capillary structure is a groove-like structure formed by a plurality of spaced apart protrusions and a groove formed between adjacent protrusions, wherein the first capillary structure and the second capillary structure are attached to each other, and the tube body is in the same a capillary structure and a region other than the second capillary structure form a two-spaced vapor passage, the first capillary structure being disposed obliquely in alignment with the second capillary structure, the second capillary structure being attached to the first capillary structure One side or one side of the second capillary structure is attached to the first capillary structure. The flat heat pipe of claim 1, wherein the first capillary structure is bonded to one side of the tube body, and the second capillary structure is bonded to the other side of the tube body, The first capillary structure and the second capillary structure each form a vapor passage on both sides of the tube body. The flat heat pipe of claim 2, wherein the pipe body comprises a top plate and a bottom plate opposite to the top plate, and one side of the first capillary structure is coupled to the bottom plate of the pipe body, One side of the second capillary structure is coupled to the top plate of the pipe body, the first capillary structure is not bonded to the other side of the bottom plate of the pipe body, and the second capillary structure is not bonded to the top plate of the pipe body. The other side of the upper side fits together. The flat heat pipe according to claim 17, wherein a side of the second capillary structure that is attached to the first capillary structure is smaller than a size of the second capillary structure away from the first capillary structure. One side of the size, the second capillary structure is attached to one side of the first capillary structure. The flat heat pipe according to claim 1, wherein the second capillary structure is rectangular In a body shape, one end of the second capillary structure is attached to the first capillary structure. The flat heat pipe according to claim 1, wherein the second capillary structure is a triangular prism shape or a rectangular parallelepiped shape, and the other side of the second capillary structure not bonded to the tubular body is attached to the same Said on the first capillary structure. The flat heat pipe of claim 1, wherein the protrusions of the first capillary structure are equidistantly spaced and the tips are flush, and a portion of the protrusions are embedded in the second capillary structure. A method for manufacturing a flat heat pipe includes the steps of: providing a rod body having a cylindrical shape, an opening and a notch formed on an outer circumferential surface thereof; and providing a round tube, the round tube being hollow, including an arc a first portion of the shape and an arcuate second portion connected to the first portion, an arcuate rib at the inner top end of the first portion projecting toward the center of the circular tube, the length of the first portion in the circumferential direction being much smaller than the second portion The circumferential length, the inner diameter of the second portion is equivalent to the outer diameter of the rod body, the rod body is inserted into the round tube, and the rib of the first portion of the round tube is received in the opening; the metal powder is filled in the location In the notch of the rod body in the circular tube, the metal powder is sintered at a high temperature to form a second capillary structure; the rod body is taken out, and the ribs of the first portion of the circular tube are etched to form a plurality of spaced protrusions and adjacent protrusions Forming a groove therebetween, the protrusions and the grooves together form a first capillary structure, the first and second capillary structures are left on the inner wall of the circular tube; and the round tube is flattened to form a flat heat pipe, Making the second capillary structure Cooperating with the first capillary structure, the flat heat pipe forms a second spaced vapor passage in a region other than the first capillary structure and the second capillary structure, and when the round pipe is flattened, the first The capillary structure is obliquely aligned with the second capillary structure. The method of manufacturing a flat heat pipe according to claim 8, wherein the opening is disposed opposite to the notch. The method for manufacturing a flat heat pipe according to claim 9, wherein the gap is horizontal The cross section is curved, and the cross section of the second capillary structure corresponds to an arc shape before the rod body is taken out and the flat tube is flattened. The method for manufacturing a flat heat pipe according to claim 10, wherein the second capillary structure is a rectangular parallelepiped shape after the round pipe is flattened. The method for manufacturing a flat heat pipe according to claim 9, wherein the notch is a flat shape, and the second capillary structure has a straight side before the rod is removed after the rod body is taken out. And an arcuate edge connected to the straight edge, the arcuate edge being bonded to an inner surface of the circular tube. The method for manufacturing a flat heat pipe according to claim 12, wherein, after the round pipe is flattened, a size of a side of the second capillary structure that is bonded to the first capillary structure is smaller than the first The second capillary structure is away from the size of one side of the first capillary structure. The method for manufacturing a flat heat pipe according to claim 9, wherein in the process of flattening the round pipe, the first capillary structure is pressed by the second capillary structure and partially embedded in the first In the second capillary structure.