US20070271787A1

US20070271787A1 - Methods for manufacturing heat sink having relatively high aspects ratio thereof

Info

Publication number: US20070271787A1
Application number: US11/419,820
Authority: US
Inventors: Robert Liang
Original assignee: Malico Inc
Current assignee: Malico Inc
Priority date: 2006-05-23
Filing date: 2006-05-23
Publication date: 2007-11-29

Abstract

Methods for manufacturing a heat sink having a central cavity, a taper core, a plurality of fins and a base plate integrally formed with the taper core and the fins are provided. The first proposed method includes the steps of: (a) making a die having a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness so as to stand a relatively high pressure and achieve a relatively high aspect ratio of the heat sink; (b) putting a material into the die; (c) pressing the material with the relatively high pressure to form the heat sink integrally such that the heat sink would have a relatively high material crystal density; and (d) removing the heat sink from the die.

Description

FIELD OF THE INVENTION

The present invention relates to methods for manufacturing a heat sink having a central cavity, a core, a plurality of fins and a base plate and more particularly for manufacturing a heat sink having a central cavity, a taper core, a plurality of fins and a base plate integrally formed with the taper core and the fins with a relatively high aspect ratio.

BACKGROUND OF THE INVENTION

Due to the dramatically increasing requirements and higher standards in heat dissipation, a kind of heat sinks with a plurality of fins, a core, a central cavity and a base plate in contacting with a heat source, which could be an electronic component such as a CPU, are commonly used for properly dissipating the heat generated by the heat source nowadays (e.g., see U.S. Pat. No. 5,828,551). To further enhance the heat dissipation, heat sinks having the central portion of the base plate made of a relatively high conductivity material with larger thermal conductivity than that of the main material of the heat sink are also frequently employed (e.g., see U.S. Pat. No. 6,851,186).
Please refer to FIG. 1( a), which is a schematic diagram showing a heat sink 10 in the prior art as aforementioned, which includes a plurality of fins 11 (e.g., fins 11A, 11B, 11C etc.), a taper core 12, a central cavity 13, and a base plate 14 having an array of standoffs 15A, 15B, 15C, etc. In FIG. 1( b), it is an exploded perspective view of the heat sink 10 of FIG. 1( a). The base plate 14 of FIG. 1( b) is shown with an array of holes 141, 142, 143 and 144 etc. for respectively receiving the standoffs 15A, 15B, 15C, etc.
Furthermore, a kind of heat sinks, each of which includes the aforementioned components, a plurality of fins, a taper core, a central cavity and a base plate integrally formed with the taper core and the fins, and also includes a pedestal on the bottom-surface of the base plate to further enhance the heat dissipation of a heat source, e.g., an electronic component, are also widely used. FIG. 2( a) is a schematic diagram showing another heat sink 20 in the prior art as above-mentioned, which includes a plurality of fins 21 (e.g., fins 21A, 21B, 21C etc.), a taper core 22, a central cavity 23, and a base plate 24 receiving an array of standoffs 25A, 25B, 25C, etc. Please refer to FIG. 2( b), which is a cross sectional view of the heat sink 20 of FIG. 2( a). Notice that a pedestal 26 is also includes on the bottom surface of the base plate 24 of the heat sink 20 and the base plate 24 is integrally formed with the heat sink 20 as shown in FIG. 2( b).
One with an ordinary skill in the field would know that the performance of the heat sink 10/20 as shown in FIGS. 1( a) and 2(a) depends on three distinctive features. The first feature is that the core 12/22 provides efficient heat transfer from the heat source to the plurality of fins 21 and speeds airflow through the heat sink. The second feature is that the heat sink 10/20 maintains a two-pass heat exchange. Air is pulled in through the fins 11/21 at the top of the heat sink 10/20 and then pushed out through the fins 11/21 at the bottom. The third feature is that the slanting of the fins 11 produces non-turbulent airflow, which aids heat transfer.
In the prior art, a method for manufacturing the aforementioned heat sinks 10, as shown in FIGS. 1( a) and 1(b), includes the steps of:

- (a) providing a material 1 (as shown in FIG. 3( a));
- (b) machining a top of the material 1 to form a central cavity 13 (as shown in FIG. 3( b));
- (c) sawing the top of the material 1 to form a plurality of fins 11 having a specific degree of slant and a taper core 12 (as shown in FIG. 3( c));
- (d) providing a base plate 14 having holes 141-144 etc. (as shown in FIG. 3( d)); and
- (e) assembling the base plate 14 with the taper core 13 to form the heat sink 10 (as shown in FIG. 3( d)).

In the step (a) of the above-mentioned method, the material 1, which has a specific size, is provided by producing a raw material 2 from an extrusion procedure firstly and by cutting the raw material 2 by a tool 3 secondly (as shown in FIG. 3( a)). And in the step (c), a saw 4 is employed to saw the material 1 so as to generate the plurality of fins 11 (as shown in FIG. 3( c)). One with an ordinary skill in the field would know that the above-mentioned method has the drawbacks that relatively the material is wasted, the whole procedure is time-consuming and the defective rate of the manufactured heat sink 10 is higher.
An improvement regarding the performance of the heat sinks (e.g., 10/20 as shown in FIGS. 1( a)-1(b) and 2(a)-2(b)) could be achieved by increasing the aspect ratio of the heat sink, which is one of the ratio of the height of a fin to the distance between two neighboring fins and the ratio of the height of a fin to the thickness of a fin, through a tooling procedure for manufacturing the die with a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness to stand a relatively high pressure and achieve a relatively high aspect ratio of the heat sink and forming the base plate integrally with the heat sink so as to increase the heat transfer and save the time and material.
Keeping the drawbacks of the prior art in mind, and employing experiments and research full-heartily and persistently, the applicant finally conceived methods for manufacturing a heat sink having relatively high aspect ratio thereof. In the field, it is known that the upper limit of the aspect ratio of the heat sink is 100 and a breaking through in reaching this upper limit is achieved through the proposed methods for manufacturing the heat sink in the present invention.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to propose methods for manufacturing a heat sink having relatively high aspect ratio thereof.
According to the first aspect of the present invention, the method for manufacturing a heat sink having a central cavity, a taper core, a plurality of fins and a base plate integrally formed with the taper core and the fins includes the steps of: (a) making a die having a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness so as to stand a relatively high pressure and achieve a relatively high aspect ratio of the heat sink; (b) putting a material into the die; (c) pressing the material with the relatively high pressure to form the heat sink integrally such that the heat sink would have a relatively high material crystal density; and (d) removing the heat sink from the die.
Preferably, the relatively high surface hardness, the specific inner hardness, the specific surface friction and the specific toughness are achieved through a specific tooling procedure including: a specific heat treating procedure, a specific polishing procedure and a specific coating procedure.
Preferably, the specific coating procedure is employed to coat a specific alloy of titanium and nickel on the die.
Preferably, the specific inner hardness is within a range of 50 HRC (Hardness: Rockwell C Scale) to 70 HRC.
Preferably, the relatively high aspect ratio of the heat sink is one of a ratio of a height of one of the fins to a distance between two neighboring ones of the fins and a ratio of the height to a thickness of one of the fins, the relatively high aspect ratio of the heat sink is equal to 100 preferably, a maximum value of the height is decided based at least in part on the specific surface friction, and a minimum value of one of the distance and the thickness is decided based at least in part on the relatively high surface hardness, the specific inner hardness and the specific toughness.
Preferably, a heat source contacts the base plate.
Preferably, the method further includes a step of: (e) forming a plurality of holes on the base plate, in which each of the holes is employed for receiving a standoff.
Preferably, the base plate further includes a first side, a second side and a pedestal, the pedestal is integrally formed on the first side of the base plate, the taper core is integrally formed on the second side of the base plate, and the step (e) further comprises a step of: (e1) machining the base plate into the pedestal.
Preferably, the pedestal is employed for contacting the heat source.
According to the second aspect of the present invention, the method for manufacturing a heat sink having a taper core, a plurality of fins and a base plate integrally formed with the taper core and the fins includes the steps of: (a) making a die having a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness so as to stand a relatively high pressure and achieve a relatively high aspect ratio of the heat sink; (b) putting a main material having a positioning cavity into the die; (c) placing a relatively high conductivity material into the positioning cavity; (d) pressing the main material and the relatively high conductivity material with the relatively high pressure to form the heat sink integrally such that the heat sink would have a relatively high material crystal density, in which the relatively high conductivity material forms a central part of the base plate, and the main material forms a surrounding part of the base plate; and (e) removing the heat sink from the die.
Preferably, the method further includes the steps of: (f) forming a plurality of holes on the base plate, in which each of the holes is employed for receiving a standoff.
Preferably, the base plate further includes a pedestal integrally formed on the base plate.
Preferably, the step (f) further includes a step of: (f1) machining the base plate into the pedestal.
Preferably, the positioning cavity is employed for positioning the relatively high conductivity material.
Preferably, the relatively high conductivity material has a thermal conductivity greater than that of the main material.
The present invention may best be understood through the following descriptions with reference to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a schematic diagram showing a heat sink in the prior art;

FIG. 1( b) is an exploded perspective view of the heat sink of FIG. 1( a);

FIG. 2( a) is a schematic diagram showing another heat sink in the prior art;

FIG. 2( b) is a cross sectional view of the heat sink of FIG. 2( a);

FIGS. 3( a)-3(c) are the schematic diagrams respectively showing the results of the steps (a)-(c) of a method in the prior art for manufacturing the heat sink of FIGS. 1( a) and 1(b);

FIG. 3( d) is a schematic diagram showing the steps (d) and (e) of the method in the prior art for manufacturing the heat sink of FIGS. 1( a) and 1(b);

FIG. 4( a) is a schematic diagram showing that a material is putting into a die at the end of the step (b) of the first proposed method for manufacturing a heat sink in the present invention;

FIG. 4( b) is a schematic diagram showing that the material is pushing under pressure to form a semi-product of the first preferred embodiment of the heat sink at the end of the step (c) of the first proposed method for manufacturing a heat sink in the present invention;

FIG. 4( c) is a schematic diagram showing a perspective view from the bottom of the semi-product of the first preferred embodiment of the heat sink at the end of the step (d) of the first proposed method for manufacturing a heat sink in the present invention;

FIG. 4( d) is a schematic diagram showing a perspective view from the top of a final-product of the first preferred embodiment of the heat sink at the end of the step (e) of the first proposed method for manufacturing a heat sink in the present invention;

FIG. 5( a) is a schematic diagram showing a main material having a positioning cavity and a relatively high conductivity material, which are employed in the second proposed method for manufacturing the second preferred embodiment of a heat sink in the present invention;

FIG. 5( b) is a schematic diagram showing that the relatively high conductivity material is placing into the positioning cavity at the end of the step (c) of the second proposed method for manufacturing the heat sink in the present invention;

FIG. 5( c) is a schematic diagram showing that the relatively high conductivity material and the main material are pushing under pressure to form a semi-product of the second preferred embodiment of the heat sink at the end of the step (d) of the second proposed method for manufacturing a heat sink in the present invention;

FIG. 5( d) is a schematic diagram showing a perspective view from the bottom of the semi-product of the second preferred embodiment of the heat sink at the end of the step (e) of the second proposed method for manufacturing a heat sink in the present invention;

FIG. 5( e) is a schematic diagram showing a perspective view from the top of a final-product of the second preferred embodiment of the heat sink at the end of the step (f) of the second proposed method for manufacturing a heat sink in the present invention;

FIG. 6 is a schematic diagram showing a perspective view from the bottom of a final-product of the third preferred embodiment of the heat sink having a pedestal on the bottom surface of the base plate; and

FIG. 7 is a schematic diagram showing a perspective view from the bottom of a final-product of the fourth preferred embodiment of the heat sink having a pedestal on the bottom surface of the base plate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As aforementioned, the relatively better performance of the heat sinks could be achieved by increasing the aspect ratio of the heat sink through a tooling procedure for manufacturing the die 5 with a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness so as to stand a relatively high pressure and achieve a relatively high aspect ratio of the heat sink 30 (see FIGS. 4( a)-4(d)).
Please refer to FIGS. 4( a)-4(d), the first proposed method for manufacturing a heat sink 30 having a central cavity 31, a taper core 32, a plurality of fins 33 and a base plate 34 integrally formed with the taper core 32 and the fins 33 includes the steps of: (a) making a die 5 having a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness so as to stand a relatively high pressure and achieve a relatively high aspect ratio of the heat sink; (b) putting a material 1 into the die 5; (c) pressing the material 1 with the relatively high pressure to form the heat sink 30 integrally such that the heat sink 30 would have a relatively high material crystal density; and (d) removing the heat sink 30 from the die 5. Besides, the first proposed method further includes a step of: (e) forming a plurality of holes 341-343 etc. on the base plate 34, in which each of the holes is employed for receiving a standoff (see FIGS. 4( d)).
In FIG. 4( a), it is a schematic diagram showing that a material 1 is putting into the die 5 at the end of the step (b) of the first proposed method, in which the force die part 51 used to press the material 1 has a pushing head 511 and the forming die part 52 of the die 5 has a receiving recess 521 where the material 1 is received and a withdraw push pin 522 for removing a semi-product of the heat sink 30. The receiving recess 521 has a bottom surface 5211 with a plurality of holes 5212 for projecting the fins 33 of the heat sink 30. FIG. 4( b) is a schematic diagram showing that the material 1 is pushing under pressure to form a semi-product 35 of the heat sink 30 at the end of the step (c) of the first proposed method. Please refer to FIG. 4( c), which is a schematic diagram showing a perspective view from the bottom of the semi-product 35 of the first preferred embodiment of the heat sink 30 at the end of the step (d) of the first proposed method, which includes the central cavity 31 (not shown), the taper core 32 (not shown), the plurality of fins 33 and the base plate 34. In FIG. 4( d), it is a schematic diagram showing a perspective view from the top of a final-product of the first preferred embodiment of the heat sink 30 including the central cavity 31, the taper core 32, the plurality of fins 33 and the base plate 34 having the plurality of holes 341-343 etc. at the end of the step (e) of the first proposed method.
The aforementioned die 5 is relatively accurate in producing near net shape semi-product such that the whole process for manufacturing the heat sink 30 is relatively quick and material saving, and the die 5 is relatively more expensive to be made of on the other hand. Once pushing the material 1 under a relatively high pressure in the die 5, the cavity 31, the core 32, the plurality of fins 33 and the base plate 34 are all formed immediately except for the plurality of holes 341-343 etc. on the base plate 34, which could be finished in only one more step of drilling.
To further enhance the heat dissipation, heat sinks each having a central cavity, a taper core, a plurality of fins and a base plate with the central portion of the base plate made of a relatively high conductivity material having larger thermal conductivity than that of the main material of the heat sink are in need. Please refer to FIGS. 5( a)-5(e), a second method for manufacturing the above-mentioned heat sinks is proposed and described as follows.
The second proposed method for manufacturing a heat sink 40 having a central cavity 41, a taper core 42, a plurality of fins 43 and a base plate 44 integrally formed with the taper core 42 and the fins 43 includes the steps of: (a) making a die 6 having a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness so as to stand a relatively high pressure and achieve a relatively high aspect ratio of the heat sink; (b) putting a main material 7 having a positioning cavity 71 into the die 6; (c) placing a relatively high conductivity material 8 into the positioning cavity 71; (d) pressing the main material 7 and the relatively high conductivity material 8 with the relatively high pressure to form the heat sink 40 integrally such that the heat sink 40 would have a relatively high material crystal density, in which the relatively high conductivity material 8 forms a central part 441 of the base plate 44, and the main material 7 forms a surrounding part 442 of the base plate 44; and (e) removing the heat sink 40 from the die 6 (see FIGS. 5( a)-5(d)). Besides, the second proposed method further comprises the steps of: (f) forming a plurality of holes 441-443 etc. on the base plate 44, in which each of the holes is employed for receiving a standoff (see FIGS. 5( e)).
In FIG. 5( a), it is a schematic diagram showing a main material 7 having positioning cavity 71 and a relatively high conductivity material 8, which are employed in the second proposed method for manufacturing the second preferred embodiment of a heat sink 40 in the present invention. The relatively high conductivity material 8 (For example: copper) has higher heat transfer conductivity than that of the main material 7 (For example: aluminum), and the positioning cavity 71 is employed for positioning the relatively high conductivity material 8.
FIG. 5( b) is a schematic diagram showing that the relatively high conductivity material 8 is placing into the positioning cavity 71 of the main material 7 at the end of the step (c) of the second proposed method. Where the force die part 61 used to press the relatively high conductivity material 8 and the main material 7 has a pushing head 611 and the forming die part 62 of the die 6 has a receiving recess 621 where the main material 7 is received and a withdraw push pin 622 for removing a semi-product of the heat sink 40. The receiving recess 621 has a bottom surface 6211 with a plurality of holes 6212 for projecting the fins 43 of the heat sink 40. Please refer to FIG. 5( c), which is a schematic diagram showing that the relatively high conductivity material 8 and the main material 7 are pushing under pressure to form the semi-product 45 of the second preferred embodiment of the heat sink 40 at the end of the step (d) of the second proposed method. In FIG. 5( d), it is a schematic diagram showing a perspective view from the bottom of the semi-product 45 of the second preferred embodiment of the heat sink 40 at the end of the step (e) of the second proposed method, which includes the central cavity 41 (not shown), the taper core 42 (not shown), the plurality of fins 43 and the base plate 44. In which, the base plate 44 includes a central part 441 formed by the relatively high conductivity material 8 and a surrounding part 442 formed by the main material 7 at the end of the step (e) of the second proposed method for manufacturing a heat sink 40 in the present invention. FIG. 5( e) is a schematic diagram showing a perspective view from the top of the final-product of the second preferred embodiment of the heat sink having the central cavity 41, the taper core 42, the plurality of fins 43 and the base plate 44 with the plurality of holes 441-443 etc. at the end of the step (f) of the second proposed method for manufacturing a heat sink 40 in the present invention.
Please refer to FIG. 6, which is a schematic diagram showing a perspective view from the bottom of a final-product of the third preferred embodiment of the heat sink 50 including a central cavity (not shown), a taper core (not shown), a plurality of fins 53 and a pedestal 55 on the bottom surface of the base plate 54 to further enhance the heat transfer. The central cavity and the taper core of the final-product of the third preferred embodiment of the heat sink 50 are the same as those of the first preferred embodiment (31 and 32) of the heat sinks 30, and the included pedestal 55 is made of the material 1 and is manufactured by following the steps of the first proposed method except that the step (e) of the first proposed method further includes a step of: (e1) machining the base plate 54 into the pedestal 55.
In FIG. 7, it is a schematic diagram showing a perspective view from the bottom of a final-product of the fourth preferred embodiment of the heat sink 60 including a central cavity (not shown), a taper core (not shown), a plurality of fins 63, a base plate 64 and a pedestal 65 on the bottom surface of the base plate 64 to further enhance the heat transfer. The central cavity and the taper core of the final-product of the fourth preferred embodiment of the heat sink 60 are the same as those of the second preferred embodiment (41 and 42) of the heat sink 40. The included pedestal 65 is made of the relatively high conductivity material 8 to form a central portion of the pedestal 651 and is made of the main material 7 to form a surrounding portion 652 of the pedestal 65, and the pedestal 65 could also be totally formed by the relatively high conductivity material 8. The pedestal 65 is manufactured by following the steps of the second proposed method except that the step (f) of the second proposed method further includes a step of: (f1) machining the base plate 64 into the pedestal 65.
In conclusion, the present invention would effectively improve the drawbacks of the prior art, further enhance the heat transfer through the heat sinks having the relatively high aspect ratio, save the material/time of the whole process so as to lower the manufacturing costs and improve the quality of the heat sinks through the proposed methods. Thus, the present invention has its value in the industry, and the purpose of developing the present invention is achieved.
While the invention has been described in terms of what are presently considered to be the most practical and preferred embodiments, it is to be understood that the invention need not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures. Therefore, the above description and illustration should not be taken as limiting the scope of the present invention which is defined by the appended claims.

Claims

1. A method for manufacturing a heat sink having a central cavity, a taper core, a plurality of fins and a base plate integrally formed with said taper core and said fins, comprising the steps of:

(a) making a die having a relatively high surface hardness, a specific inner hardness, a specific surface friction and a specific toughness so as to stand a relatively high pressure and achieve a relatively high aspect ratio of said heat sink;

(b) putting a material into said die;

(c) pressing said material with said relatively high pressure to form said heat sink integrally such that said heat sink would have a relatively high material crystal density; and

(d) removing said heat sink from said die.

2. The method according to claim 1, wherein said relatively high surface hardness, said specific inner hardness, said specific surface friction and said specific toughness are achieved through a specific tooling procedure comprising: a specific heat treating procedure, a specific polishing procedure and a specific coating procedure.

3. The method according to claim 2, wherein said specific coating procedure is employed to coat a specific alloy of titanium and nickel on said die.

4. The method according to claim 2, wherein said specific inner hardness is within a range of 50 HRC (Hardness: Rockwell C Scale) to 70 HRC.

5. The method according to claim 2, wherein said relatively high aspect ratio of said heat sink is one of a ratio of a height of one of said fins to a distance between two neighboring ones of said fins and a ratio of said height to a thickness of one of said fins, said relatively high aspect ratio of said heat sink is equal to 100 preferably, a maximum value of said height is decided based at least in part on said specific surface friction, and a minimum value of one of said distance and said thickness is decided based at least in part on said relatively high surface hardness, said specific inner hardness and said specific toughness.

6. The method according to claim 1, wherein said base plate contacts a heat source.

7. The method according to claim 6 further comprising a step of:

(e) forming a plurality of holes on said base plate, wherein each of said holes is employed for receiving a standoff.

8. The method according to claim 7, wherein said base plate further comprises a first side, a second side and a pedestal, said pedestal is integrally formed on said first side of said base plate, said taper core is integrally formed on said second side of said base plate, and said step (e) further comprises a step of: (e1) machining said base plate into said pedestal.

9. The method according to claim 8, wherein said pedestal is employed for contacting said heat source.

10. A method for manufacturing a heat sink having a central cavity, a taper core, a plurality of fins and a base plate integrally formed with said taper core and said fins, comprising the steps of:

(b) putting a main material having a positioning cavity into said die;

(c) placing a relatively high conductivity material into said positioning cavity;

(d) pressing said main material and said relatively high conductivity material with said relatively high pressure to form said heat sink integrally such that said heat sink would have a relatively high material crystal density, wherein said relatively high conductivity material forms a central part of said base plate, and said main material forms a surrounding part of said base plate; and

(e) removing said heat sink from said die.

11. The method according to claim 10 further comprising a step of:

(f) forming a plurality of holes on said base plate, wherein each of said holes is employed for receiving a standoff.

12. The method according to claim 10, wherein said base plate further comprises a pedestal integrally formed on said base plate.

13. The method according to claim 12, wherein said step (f) further comprises a step of:

(f1) machining said base plate into said pedestal.

14. The method according to claim 10, wherein said positioning cavity is employed for positioning said relatively high conductivity material.

15. The method according to claim 10, wherein said relatively high conductivity material has a thermal conductivity greater than that of said main material.