Abstract:
An exemplary method for manufacturing a heat dissipation apparatus includes, firstly, providing a fin assembly including a stack of fins spaced from each other. Each fin defines a through hole therein, and includes a collar formed at an edge of the through hole. Then a heat pipe is provided, and inserted in the through holes of the fins. Next, two opposing punching tools are provided. Each punching tool defines a series of recesses. The subassembly of the heat pipe and fins is positioned between the two punching tools, with the collar of each fin located between two corresponding recesses of the two punching tools. The two punching tools punch the collars of the fins from two opposite sides of the collars. Thereby, the collars shrink inwardly and press the heat pipe to deform until the heat pipe is fittedly mounted in the collars of the fins.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to methods for manufacturing heat dissipation apparatuses, and particularly to a method for manufacturing a heat dissipation apparatus having a heat pipe. 
     2. Description of Related Art 
     With developments in electronics technology, increased performance of electronic components such as CPUs (central processing units) has been achieved. However, such electronic components generate increased levels of heat, which must be dissipated promptly. Conventionally, a heat dissipation apparatus which includes a fin assembly combined with a heat pipe is used to remove the heat generated by the electronic component. 
     The fin assembly includes a plurality of fins. Each fin defines a through hole therein, for extending of the heat pipe therethrough. In order to ensure a high heat conductive efficiency between the heat pipe and the fins, typically, the heat pipe is soldered in the through holes of the fins through a soldering process. However, solder is typically composed of a lot of heavy metals, such as lead, tin or others, which if mishandled can cause permanent damage to humans or the environment. 
     Therefore, what is needed is a method for manufacturing a heat dissipation apparatus which can overcome the described limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric, assembled view of a heat dissipation apparatus manufactured by a method in accordance with a first embodiment of the present disclosure. 
         FIG. 2  is an isometric view of a punching tool used in the method of the first embodiment. 
         FIGS. 3-5  are schematic, front views illustrating sequential steps of the method for manufacturing the heat dissipation apparatus of  FIG. 1 . 
         FIG. 6  is a schematic, front view illustrating a single step of a method for manufacturing the heat dissipation apparatus of  FIG. 1  in accordance with a second embodiment of the present disclosure. 
         FIG. 7  is a schematic, front view of part of a heat dissipation apparatus preform before a punching process of a method for manufacturing the heat dissipation apparatus in accordance with a third embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a heat dissipation apparatus  100  manufactured through a manufacturing method in accordance with a first embodiment of the present disclosure is shown. The heat dissipation apparatus  100  includes a fin assembly  10 , and a heat pipe  20  extending through the fin assembly  10 . 
     The fin assembly  10  includes a plurality of plate-shaped metallic fins  11  stacked together and spaced apart from each other at constant intervals. An air passage is defined between every two adjacent fins  11 . Each of the fins  11  is rectangular and defines a through hole  112  therein, for extending of the heat pipe  20  therethrough. The through holes  112  are circular. An annular collar  114  extends perpendicularly from each fin  11  at an edge of the through hole  112 . The heat pipe  20  is interferentially fixed in the collar  114  of each fin  11  (see below). 
     Referring also to  FIGS. 2 and 3 , during manufacturing of the heat dissipation apparatus  100 , a first punching tool  40 , a second punching tool  50  and a punching process are applied. The first punching tools  40  includes a handle portion  41 , and a plurality of punching units  42  extending downwardly from the handle portion  41 . The handle portion  41  is strip-shaped. The punching units  42  are evenly spaced from each other along a longitudinal direction of the handle portion  41 . A distance between every two adjacent punching units  42  exceeds a thickness of each fin  11 . Each of the punching units  42  is rectangular, and has a thickness less than a distance between every two adjacent fins  11 . A free end of each punching unit  42  away from the handle portion  41  defines a recess  421  therein. The recess  421  has an arc-shaped edge. The second punching tool  50  is substantially identical to the first punching tool  40 . That is, the second punching tool  50  includes a handle portion  51  and a plurality of punching units  52  formed on the handle portion  51 , with each of the punching units  52  defining a recess  521  therein. 
     Referring to  FIG. 3 , before the punching process, the heat pipe  20  has a circular cross section. An outer diameter of the heat pipe  20  is less than a diameter of the through hole  112  of each fin  11 , and less than an inner diameter of the collar  114  of each fin  11 , in order that the heat pipe  20  can be loosely inserted in the through hole  112  and the collar  114  of the fin  11 . Typically, the diameter of the heat pipe  20  is 80% to 99% of the diameter of the through hole  112  of the fin  11  (or the inner diameter of the collar  114 ) before the punching process. In this embodiment, the diameter of the heat pipe  20  is substantially 90% of the diameter of the through hole  112  of the fin  11  (or the inner diameter of the collar  114 ) before the punching process. The first punching tool  40  and the second punching tool  50  are spaced from each other. The recess  421  of the punching unit  42  of the first punching tool  40  faces the recess  521  of a corresponding punching unit  52  of the second punching tool  50 . The fin assembly  10  is disposed between the first punching tool  40  and the second punching tool  50 . By this arrangement, the collar  114  of each fin  11  is located between the recesses  421 ,  521  of corresponding punching units  42 ,  52  of the first punching tool  40  and the second punching tool  50 . 
     Referring to  FIGS. 4 to 5 , during the punching process, each of the first punching tool  40  and the second punching tool  50  is driven by a punch (not shown) to move toward the fin assembly  10 . The punching units  42 ,  52  of the first and second punching tools  40 ,  50  respectively enter the air passages between the fins  11  of the fin assembly  10  from two opposite directions to punch the collars  114  of the fins  11 . Each corresponding two punching units  42 ,  52  of the first punching tool  40  and second punching tool  50  punch a corresponding collar  114  of the fin  11  from two opposite sides of the collar  114 . The collar  114  shrinks inwardly due to the impact of the corresponding punching units  42 ,  52  of the first and second punching tools  40 ,  50  to cause an inner surface of the collar  114  to press a periphery of the heat pipe  20 . At the same time, the heat pipe  20  deforms correspondingly due to pressing of the collar  114  to enhance the contact between the inner surface of the collar  114  and the heat pipe  20 . When the inner surface of the collar  114  closely contacts the entire periphery of the heat pipe  20  in this way, the punching process is completed. At this time, the heat pipe  20  is fittedly mounted in the collar  114  of each fin  11 , and the first punching tool  40  and second punching tool  50  are moved away from the heat dissipation apparatus  100 . 
     In this embodiment, the recesses  42 ,  52  of the first and second punching tools  40 ,  50  are semicircular. Before the punching process, an inner diameter of the recess  42  or  52  is smaller than an outer diameter of the collar  114  but larger than an outer diameter of the heat pipe  20 , as shown in  FIG. 4 . When the recesses  421 ,  521  of the corresponding punching units  42 ,  52  of the first and second punching tools  40 ,  50  cooperatively define a round hole, the heat pipe  20  is fittedly mounted in the collar  114  of each fin  11  and the inner surface of the collar  114  of each fin  11  closely contacts the entire corresponding periphery of the heat pipe  20 . Understandably, in other embodiments, the recesses  421 ,  521  of the punching tools  40 ,  50  can instead be, for example, arch-shaped or semi-elliptical. 
     According to above description, in the method for manufacturing the heat dissipation apparatus  100 , each collar  114  of the fin  11  is punched by the first punching tool  40  and the second punching tool  50  from two opposite directions. The collar  114  shrinks and the heat pipe  20  deforms, so as to cause the heat pipe  20  to be fittedly mounted in the collar  114  of each fin  11  through an interference fit rather than through, e.g., soldering. This avoids the use of solder comprised of heavy metals. 
     In addition, during the punching process of the manufacturing method for the heat dissipation apparatus  100 , the heat pipe  20  is fittedly mounted in the collar  114  of each fin  11  with the heat pipe  20  deforming only slightly. This avoids damage to an inner structure of the heat pipe  20  which may otherwise be caused by, e.g., directly punching the heat pipe  20  and significantly deforming the heat pipe  20 . 
     Furthermore, the method for manufacturing the heat dissipation apparatus  100  causes the collar  114  of each fin  11  to totally contact the heat pipe  20 . This helps avoid loosening of the contact surface between the fins  11  and the heat pipe  20 . In turn, this advantageously promotes a heat conductive efficiency between the fins  11  and the heat pipe  20 . In other words, a heat dissipation efficiency of the heat dissipation apparatus  100  is enhanced. 
     Referring to  FIG. 6 , this is a schematic view of a single step of a method for manufacturing the heat dissipation apparatus  100  in accordance with a second embodiment of the present disclosure. In this embodiment, the first punching tool  40  is placed above the second punching tool  50 , and the fin assembly  10  is prefixed on the second punching tool  50 . By this arrangement, each fin  11  of the fin assembly  10  is located between every two adjacent two punching units  52  of the second punching tool  50 , and the collar  114  of each fin  11  is held in a recess  521  of a corresponding punching unit  52  of the second punching tool  50 . The first punching tool  40  is driven by a punch (not shown) to punch the fin assembly  10  fixed on the second punching tool  50 , similar to the procedure shown in  FIG. 4  and  FIG. 5 . 
     Referring to  FIG. 7 , this is a front view of part of a heat dissipation apparatus  100   a  before a punching process of a method for manufacturing the heat dissipation apparatus  100   a  in accordance with a third embodiment of the present disclosure. In this embodiment, a collar  114   a  of each fin  11   a  of the heat dissipation apparatus  100   a  defines two slots  1141  therein. Each of the slots  1141  is strip-shaped, and extends parallel to an axis of the collar  114   a . The two slots  1141  of the collar  114   a  face each other to divide the collar  114   a  into two equal parts. This allows the collar  114   a  to shrink more easily during the punching process. When the punching process is completed, the two slots  1141  of the collar  114   a  are substantially closed due to the shrinkage of the collar  114   a . In this embodiment, the collar  114   a  defines two slots  1141 . Understandably, in other embodiments, one slot  1141  or more than two slots  1141  can be defined in the collar  114   a.    
     It is to be understood, however, that even though numerous characteristics and advantages of the exemplary embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the embodiments to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.