TWI497026B - 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 comprising a hollow flat tube body and a first capillary structure and a second capillary structure disposed in the tube body, the first capillary structure being formed by bending and laminating a multi-voided steel mesh, the second capillary structure Formed by sintering of the metal powder, the first capillary structure and the second capillary structure are bonded to each other, and the tube body forms a vapor passage in a region other than the first capillary structure and the second capillary structure.

A method for manufacturing a flat heat pipe, comprising the steps of: providing a rod body having a cylindrical shape, an opening and a notch formed on an outer circumferential surface thereof; providing a first capillary structure; providing a round tube, wherein the round tube is Hollow, the inner diameter of the circular tube is equal to the outer diameter of the rod body, and the rod body and the first capillary structure are inserted into the circular tube so that the first capillary structure is located at the opening of the rod body Between the tube wall of the circular tube; providing a plurality of metal powders, filling the metal powder into the notch of the rod body located in the circular tube, sintering the metal powder at a high temperature to form a second capillary structure; taking out the rod body, The first and second capillary structures are left in the circular tube and respectively attached to a part of the inner wall of the circular tube; and the round tube is flattened to form a flat heat pipe, so that the second capillary structure is attached to In the first capillary structure, a vapor passage is formed in the flat heat pipe in a region other than the first capillary structure and the second capillary structure.

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 And the first and second capillary structures are attached to each other, and when the heat pipe works, the working medium can penetrate each other between the first and second capillary structures, and has a large capillary force and a comparative High permeability and low thermal resistance make the heat pipe have good heat transfer performance.

10, 20, 30, 40‧‧‧ flat heat pipes

101‧‧‧Evaporation section

102‧‧‧Condensation section

11‧‧‧Body

110‧‧‧Internal space

111‧‧‧ top board

112‧‧‧floor

113, 114‧‧‧ side panels

118‧‧‧Vapor passage

12, 22, 32, 42, 15‧‧‧ first capillary structure

13, 23, 33, 43, 17, 17a‧‧‧Second capillary structure

14, 14a‧‧‧ rod body

141‧‧‧ openings

142, 142a‧‧ ‧ gap

16‧‧‧ round tube

171‧‧‧ Straight side

172‧‧‧Arc edge

18, 18a‧‧‧ Round heat pipe

10, 20, 30, 40‧‧‧ flat heat pipes

101‧‧‧Evaporation section

102‧‧‧Condensation section

11‧‧‧Body

110‧‧‧Internal space

111‧‧‧ top board

112‧‧‧floor

113, 114‧‧‧ side panels

118‧‧‧Vapor passage

12, 22, 32, 42, 15‧‧‧ first capillary structure

13, 23, 33, 43, 17, 17a‧‧‧Second capillary structure

14, 14a‧‧‧ rod body

141‧‧‧ openings

142, 142a‧‧ ‧ gap

16‧‧‧ round tube

171‧‧‧ Straight side

172‧‧‧Arc edge

18, 18a‧‧‧ Round heat pipe

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 injected into the tube body 11 (not shown). 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 longitudinal structure which is flattened into a flat solid shape by the second capillary structure 13, and a plurality of fine pores (not shown) are formed on the first capillary structure 12. In this embodiment, the first capillary structure 12 is formed by a multilayer stack of steel meshes having a plurality of pores. The first capillary structure 12 has a large porosity, so that the permeability is high and the thermal resistance is small, which facilitates the smooth flow of the working medium therein. Of course, the first capillary structure 12 can also be a single-layer steel mesh.

The first capillary structure 12 is disposed on one side of the middle portion of the tubular body 11. In this embodiment, the bottom surface of the first capillary structure 12 is closely attached to the inner surface of the bottom plate 112 of the tubular body 11, and the top surface thereof is coupled to the second capillary structure 13.

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 on the other side of the tube body 11 opposite to the first capillary structure 12, that is, the second capillary structure 13 The first capillary structure 12 is being formed. 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 tip forms a tip and is attached to the middle 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 is a porous steel mesh which is disposed on one side of the pipe body 11 (the inner surface of the bottom plate 112), and the second capillary structure 13 is formed by sintering of the metal powder. The sintered structure 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 stacked one on another. When the heat pipe 10 is in operation, the working medium penetrates between the first and second capillary structures 12 and 13, and has a large capillary force due to the sintered second capillary structure 13 and Capillary structure 12 It has a high permeability and a small heat resistance, 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) / Qmax.

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 16.7% compared with the conventional sintered heat pipe, and the average heat is simultaneously The resistance value is reduced by about 10.8% 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.

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 43.6% compared with the conventional sintered heat pipe, and the average heat is simultaneously The resistance value is reduced by about 28.9% 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, the notch 142 is not in communication with the opening 141; a hollow metal tube 16 is provided, the inner diameter of the tube 16 is approximately equal to the outer diameter of the rod 14, and the rod 14 is inserted In the circular tube 16; a first capillary structure 15 (see FIG. 6) formed by multi-layer stacking of a porous steel mesh is provided, and the first capillary structure 15 is placed in the circular tube 16 and the rod body 14. a gap between the openings 141; A plurality of metal powders are provided, and the metal powder is filled in a space between the round pipe 16 and the notch 142 of the rod body 14. When the metal powder is filled, the metal powder having a fine particle size may be first filled, and then gradually filled in. The metal powder having a relatively large particle diameter vibrates the circular tube 16 so that the metal powder is distributed along the longitudinal direction of the circular tube 16 according to the gravity factor, and after filling, the metal powder is sintered at a high temperature to form a second capillary structure 17, which is second. The cross-sectional mask of the capillary structure 17 has a straight edge 171 and a curved edge 172 connected to the straight edge 171, wherein the curved edge 172 is adhered to the inner surface of the circular tube 16; the rod body 14 is removed, as shown in the figure As shown in FIG. 6, the first and second capillary structures 15, 17 are left in the circular tube 16, and the first and second capillary structures 15, 17 are disposed opposite to each other and are respectively attached to the portion of the circular tube 16. a working medium is filled into the circular tube 16, vacuum is drawn and the longitudinal ends of the circular tube 16 are closed to form a circular heat pipe 18; the first and second capillary structures 15, 17 are directly aligned The circular heat pipe 18 forms the heat pipe 10 in the first embodiment, wherein the round pipe 16 is flattened and shaped a flat tube body 11, the second capillary structure 17 is flattened to form a second triangular structure 13 having a substantially triangular prism shape, and a side of the second capillary structure 13 having a smaller size, that is, a bottom side is attached to the first On the top surface of the capillary structure 17, the first capillary structure 15 is pressed by the second capillary structure 17 to form a first capillary structure 12 having a substantially rectangular cross section.

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 leftward position in the 11th, the second capillary structure 23 is disposed in the tube The middle right portion of the body 11 is obliquely aligned with the first capillary structure 22, and the second capillary structure 23 is not closely attached to a side surface (the left side surface in the drawing) of the top plate 111 of the tubular body 11 It is attached to the right side of the top surface of the first capillary structure 22. Of course, the first capillary structure 22 can also be disposed at a right-right position in the tubular body 11, and the second capillary structure 23 is closely attached to a side surface (ie, the right side surface) of the top plate 111 of the tubular body 11. It is attached to the left side of the top surface of the first capillary structure 22.

When manufacturing the heat pipe 20, it is only necessary to align the first capillary structure 15 and the second capillary structure 17 in Fig. 6 obliquely to round the circular heat pipe 18.

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 17a formed in the circular heat pipe 18a is also curved. The second capillary structure 17a is crushed 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 a leftward position in the middle portion of the 11th, and the second capillary structure 43 is not attached to a side surface of the top plate 111 of the tubular body 11 (in the figure) The left side surface is closely attached to the right side of the top surface of the first capillary structure 42. Of course, the first capillary structure 42 can also be disposed in the tube body 11. In the middle right position, a side surface (ie, the right side surface) of the second capillary structure 43 that is not attached to the top plate 111 of the tube body 11 is in close contact with the left side of the top surface of the first capillary structure 42.

When the heat pipe 40 is manufactured, it is only necessary to align the second capillary structure 17a of the first capillary structure 15 in Fig. 9 with the circular heat pipe 18a.

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

Claims (13)

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 first capillary structure is formed by bending and laminating a multi-voided steel mesh, The second capillary structure is formed by sintering the metal powder, and the first capillary structure and the second capillary structure are bonded to each other to divide the internal space of the tubular body into two in the longitudinal direction, thereby forming the first capillary structure and the first capillary structure and the first capillary structure. The opposite side regions of the second capillary structure form a two-spaced vapor channel, 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 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 1, 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 has a rectangular parallelepiped shape, and 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. A method for manufacturing a flat heat pipe, comprising the steps of: providing a rod body having a cylindrical shape, an opening and a notch formed on an outer circumferential surface thereof; providing a first capillary structure; providing a round tube, wherein the round tube is Hollow, the inner diameter of the circular tube is equal to the outer diameter of the rod body, and the rod body and the first capillary structure are inserted into the circular tube so that the first capillary structure is located at the opening of the rod body Between the tube wall of the circular tube; providing a plurality of metal powders, filling the metal powder into the notch of the rod body located in the circular tube, sintering the metal powder at a high temperature to form a second capillary structure; taking out the rod body, The first and second capillary structures are left in the circular tube and respectively attached to a part of the inner wall of the circular tube; and the round tube is flattened to form a flat heat pipe, so that the second capillary structure is attached to In the first capillary structure, the first capillary structure and the second capillary structure divide the internal space of the pipe body into two in the longitudinal direction, thereby forming the first capillary structure and the second capillary heat pipe. Formation of opposite sides of the capillary structure Spaced vapor passage, when playing the flat tube, the first capillary structure and the second capillary structure is aligned obliquely. The method for manufacturing a flat heat pipe according to claim 7, wherein the cross section of the notch is curved, and the second capillary structure is transversely before the rod is removed after the rod body is taken out. The section corresponds to an arc. The method for manufacturing a flat heat pipe according to claim 8, 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 7, wherein the notch is flat, 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 10, 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 of manufacturing a flat heat pipe according to claim 7, wherein the opening is curved, and the first capillary structure is curved before the round tube is flattened. The method of manufacturing a flat heat pipe according to claim 12, wherein, in the process of flattening the round pipe, the first capillary structure is formed into a flat shape by extrusion of the second capillary structure.