Abstract:
A heat sink and a method for manufacturing a heat sink are described. A plate-like base is manufactured with a plurality of parallel grooves and a plurality of fins by an impact extrusion process. A high temperature heat treatment is performed to soften the plate-like base. The fins are positioned in corresponding grooves and an equal force is applied to both ends of the plate-like base so that the grooves are deformed and the fins are fixedly positioned. The method is simpler and significantly cheaper than that for conventional heat sinks.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a heat sink and a method for manufacturing the same, and in particular to a heat sink and a method for manufacturing a heat sink that is easily manufactured, cheap and highly efficient in heat dissipation.  
         [0003]     2. Description of Related Art  
         [0004]     Referring to  FIGS. 1 and 2 , a conventional heat sink  1  is disclosed. The conventional heat sink  1  has a plate-like base  11  and a plurality of fins  12 . The plate-like base  11  and plurality of fins  12  are manufactured by an impact extrusion process and can be made of copper. Then, thermal transfer adhesive is applied to the bottom of the fins  12  which are equidistantly separated and positioned on top surface of the plate-like base  11 .  
         [0005]     In addition, the plate-like base  11  and plurality of fins  12  can also be made of copper and aluminum, respectively. Compared with the heat sink made of copper in the prior art, the heat sink described above has less overall weight. However, when a plurality of fins  12  is connected to the plate-like base  11 , each fin  12  must individually soldered to the top surface of the plate-like base  11  by solder  13 .  
         [0006]     No matter what the plate-like base  11  and a plurality of fins  12  are made of, it is time-consuming and expensive to connect the plate-like base  11  and a plurality of fins  12  by soldering.  
         [0007]     Due to the desire for lightweight mobile electronic device, when the heat sink has less weight, it is not prone breaking during shipping. Although the conventional heat sink  1  is made of lightweight aluminum instead of the heavier copper, the weight of the conventional heat sink  1  cannot be decreased. However, the fins  12  are soldered to most of the area of the plate-like base  11  so that the weight of the conventional heat sink  1  fails to be significantly decreased.  
         [0008]     Furthermore, the plate-like base  11  of the conventional heat sink  1  abuts against a heat-generating component  21 . A fan (not shown) subsequently attached to the conventional heat sink  1  provides a cooling airflow. Because the fins  12  are equidistantly separated and positioned on the top surface of the plate-like base  11 , the cooling airflow contacts the plate-like base  11  of the conventional heat sink  1 . Then, part of the cooling airflow flows between fins  12  and another part of the cooling airflow flows in the opposite direction. Turbulent airflow thus occurs near the contact area of the fins  12  and the plate-like base  11  and generates a higher back pressure so that the fan provides less airflow and efficiency of heat dissipation is adversely impacted.  
         [0009]     Thus, there is need to develop a heat sink and a method for manufacturing a heat sink.  
       SUMMARY OF THE DISCLOSURE  
       [0010]     It is an object of the present invention to provide a heat sink and a method for manufacturing a heat sink that is easily manufactured, cheap and highly efficient in heat dissipation.  
         [0011]     It is another object of the present invention to provide a method for manufacturing a heat sink made of different materials and that is lighter and highly efficient in heat dissipation.  
         [0012]     It is another object of the present invention to provide a heat sink made of different materials and that is lighter and highly efficient in heat dissipation.  
         [0013]     It is an object of the present invention to provide a heat sink and a method for manufacturing a heat sink. The method of the present invention includes manufacturing a plate-like base with a plurality of parallel grooves and a plurality of fins by an impact extrusion process, performing a high temperature heat treatment to soften the plate-like base, and positioning the fins to corresponding grooves and applying an equal force to both ends of the plate-like base so that the grooves are deformed and the fins are fixedly positioned. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0014]     The present invention can be fully understood from the following detailed description and preferred embodiment with reference to the accompanying drawings, in which:  
         [0015]      FIG. 1  is a perspective view of a conventional heat sink;  
         [0016]      FIG. 2  is an enlarged partial view of the conventional heat sink indicated by arrow A of  FIG. 1 ;  
         [0017]      FIG. 3  is an exploded view of a heat sink in accordance with the present invention;  
         [0018]      FIG. 4  is a perspective view of a heat sink in accordance with the present invention;  
         [0019]      FIG. 5  is an enlarged partial view of the heat sink indicated by arrow A of  FIG. 4 ;  
         [0020]      FIG. 6  is a block diagram illustrating a heat sink according to one embodiment of the present invention; and  
         [0021]      FIG. 8  is a block diagram illustrating a heat sink according to another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0022]     The following detailed description is of the best presently contemplated modes of carrying out the invention. This description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating general principles of embodiments of the invention. The scope of the invention is best defined by the appended claims.  
         [0023]      FIGS. 3-5  illustrate a heat sink  3  in accordance with one embodiment of the present invention. The heat sink  3  has a plate-like base  31  and a plurality of fins  32  positioned on the plate-like base  31 . The plate-like base  31  has a central segment  311  and two flange segments  312 . The two flange segments  312  correspond to and extend from both ends of the central segment  311  in the direction of arrow Y. The central segment  311  and the two flange segments  312  have their corresponding top surfaces and bottom surfaces. The top surfaces of the central segment  311  and the two flange segments  312  are in the same plane, and the bottom surfaces of the central segment  311  and the two flange segments  312  are also in the same plane. In addition, a length of the central segment  311  in the direction of arrow X is greater than that of the two flange segments  312 . A plurality of parallel grooves  313  is located in the central segment  311  and the two flange segments  312 . Further, each of the parallel grooves  313  is U-shaped and is adapted to receive the fins  32 .  
         [0024]     Referring to  FIGS. 3 and 4 , the length of the fins  32  is greater than that of the plate-like base  31  in the direction of arrow X. Thus, middle portions  321  of the fins  32  are only in contact with the plate-like base  31 . However, two end portions  322  of the fins  32  are not in contact with the plate-like base  31 , and there are thermal transfer channels  323  between two neighboring fins  31 .  
         [0025]     Thus, the central segment  311  of the plate-like base  31  abuts against a heat-generating component  42  of a circuit board  41 . The two flange segments  312  of the plate-like base  31  are not in contact with two end portions  322  of the fins  32  so that the circuit board  41  is not in contact with the fins  32 . When the heat-generating component  42  is in use, the central segment  311  of the plate-like base  31  conducts heat generated by the heat-generating component  42  and carries heat into the fins  32  of the two flange segments  312  and the plate-like base  31 . Heat is thus vented away from the fins  32 . To increase efficiency of heat dissipation, a fan (not shown) can be installed on the heat sink  3  and cooling airflow flows in the directions indicated by arrows in  FIG. 4 . After the cooling air is blowing at the fins  32 , the cooling air is blown along the thermal transfer channels  323  between the fins  32  and is directed toward the two end portions  322  of the fins  32 . Further, a part of cooling airflow flows through the bottom of the thermal transfer channels  323 . Thus, a larger back pressure does not result to lessen the cooling airflow of the fan. The heat sink  3  of one embodiment of the present invention has an improved efficiency of heat dissipation.  
         [0026]     Referring to  FIGS. 3 and 6 , a method of manufacturing the heat sink  3  is described as follows. In step  51 , the plate-like base  31  is formed on the heat sink  3  by an impact extrusion process, and a plurality of parallel grooves  311  are formed by a stamping process. The plate-like base  31  and the fins  32  can be respectively made of copper and aluminum. In step  52 , the plate-like base  31  is placed in a high temperature furnace and the temperature within the furnace is kept between 1000-1100° C. so that the plate-like base  31  is fully softened to relieve residual stress. In step  53 , the fins  32  are respectively positioned into the parallel grooves  311  of the plate-like base  31  by a jig (not shown), and the plate-like base  31  is subjected to compressive forces as shown in  FIG. 5  so that the parallel grooves  311  are deformed to grasp the fins  32 . The plate-like base  31  and the fins  32  of the heat sink  3  are made of aluminum or copper.  
         [0027]     Referring to  FIG. 7 , in Step  54 , the plate-like base  31  is manufactured by powder metallurgy and the fins  32  are manufactured by an impact extrusion process. Because density of components made by powder metallurgy is less than that of aluminum or copper, the processing of softening the plate-like base  31  is shortened. Then, in step  55 , the fins  32  can be positioned in the parallel grooves  311  of the plate-like base  31  and the plate-like base  31  is subjected to a compressive force.  
         [0028]     Thus, advantages of the present invention are described in the following:  
         [0029]     1. The manufacturing process is straightforward and has a low cost. The plate-like base  31  is formed on the heat sink  3  by an impact extrusion process, and a plurality of parallel grooves  311  is formed by a stamping process. The plate-like base  31  is placed in a high temperature furnace. The fins  32  are respectively positioned in the parallel grooves  311  of the plate-like base  31 , and the plate-like base  31  is subjected to compressive forces. The parallel grooves  311  are deformed to grasp the fins  32 . Thus, compared with the conventional method, the present invention provides a simplified method and is significantly cheaper.  
         [0030]     2. The heat sink according to present invention has improved efficiency of heat dissipation. Since the parallel grooves  311  of the plate-like base  31  of the present invention abut against the heat-generating component  42 , the two flange segments  312  of the plate-like base  31  are not in contact with two end portions  322  of the fins  32 . Thus, there is a gap between the circuit board  41  and the fins  32 . When the heat-generating component  42  is in use, the central segment  311  of the plate-like base  31  conducts heat generated by the heat-generating component  42  and carries heat into the fins  32  of the two flange segments  312  and the plate-like base  31 . Heat is vented away from the fins  32  with the help of cooling air (a fan can be installed on the heat sink  3  to increase efficiency of heat dissipation). After the cooling air is blown onto the fins  32 , the cooling air is blown along the thermal transfer channels  323  between the fins  32  and is directed toward the two end portions  322  of the fins  32 . Further, a part of cooling airflow is flows through the bottom of the thermal transfer channels  323 . Thus, a larger back pressure does not result to lessen the cooling airflow of the fan. The heat sink  3  of one embodiment of the present invention has a better efficiency of heat dissipation.  
         [0031]     3. The heat sink is lightweight.  
         [0032]     According to the present invention, the plate-like base  31  and the fins  32  of the heat sink  3  are respectively made of copper and aluminum. The present invention is able to meet the requirement of a light-weight of mobile electronic device. When the heat sink is lightweight, it is not prone to damage during transportation.  
         [0033]     4. The material of which the plate-like base  31  and the fins  32  are made can be replaced if necessary.  
         [0034]     5. There is no limitation of separation and height of the fins  32 .  
         [0035]     While the invention has been described with reference to the preferred embodiments, the description is not intended to be construed in a limiting sense. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as may fall within the scope of the invention defined by the following claims and their equivalents.