Abstract:
A board-shaped heat dissipating device includes a board body having a plane face with a recess formed thereon, a heat conducting element fitted in the recess, at least one groove formed on any one of the board body and the heat conducting element, and at least one heat pipe pressed into the groove to flush with an open side of the groove. After the heat pipe is pressed into the groove and the heat conducting element is firmly fitted in the recess, portions of the heat conducting element that are higher than the plane face are removed through a cut operation, so that the heat conducting element is flush with the plane face of the board body to reduce the space occupied by the heat dissipating device. With the above arrangements, the problem of thermal resistance can be avoided and upgraded overall heat dissipation efficiency can be achieved.

Description:
The present application is a division of U.S. patent application Ser. No. 12/535,120, filed on Aug. 4, 2009, now U.S. Pat. No. 8,353,333, titled Board-Shaped Heat Dissipating Device and Method of Manufacturing the Same, listing Ping Chen and Shu-Chun Yu as inventors. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a board-shaped heat dissipating device, and more particularly to a board-shaped heat dissipating device that occupies reduced space, provides upgraded heat dissipation efficiency, and avoids the problem of thermal resistance. The present invention also relates to a method of manufacturing the above-described board-shaped heat dissipating device. 
     BACKGROUND OF THE INVENTION 
     The heat produced by electronic elements in various electronic devices increases with the increasing computing speed and data processing capability of the electronic devices. The heat produced by the electronic elements during the operation thereof must be timely removed, lest the heat should adversely affect the operation efficiency of the electronic devices to even cause burnout of the electronic elements thereof. According to a conventional way of removing such heat, a cooling unit is provided on a top of an electronic element. The conventional cooling unit usually includes a heat sink or a plurality of radiating fins and a cooling fan, which work cooperatively to remove the produced heat. In some cases, heat pipes are further provided to cooperate with the cooling unit, so that heat source is guided by the heat pipes to distal ends of the heat pipes and be dissipated into ambient environment. However, since an electronic device usually has only very limited internal space while the number of heat-producing electronic elements in the electronic device is large, the cooling units being correspondingly provided on the electronic elements will become very close to one another in the limited internal space of the electronic device and fail to extend their cooling ability. There is also another conventional heat dissipating way in which heat pipes are embedded in one face of a heat dissipating board to thereby form a heat dissipating element capable of overcoming the drawbacks in the conventional cooling unit and heat pipes. The conventional heat dissipating board includes at least one groove formed on one face of the board for each receiving a heat pipe therein. The heat pipe transfers the heat source to a relatively cold location on the heat dissipating board, so that the heat is dissipated into ambient air from the heat dissipating board. To facilitate easy positioning of the heat pipe in the groove, the groove is usually formed with a somewhat large allowance. Therefore, there would be a clearance left between the groove and the heat pipe positioned therein. Such clearance tends to cause thermal resistance to adversely affect the heat dissipation efficiency of the conventional heat dissipating board. Further, when the heat pipe is associated with the groove through welding, the heated surface of the heat pipe will expand to adversely affect the accuracy in assembling the heat pipe to the groove. In brief, the conventional heat dissipating board has the following disadvantages: (1) poor heat dissipation efficiency; and (2) poor assembling accuracy. 
     SUMMARY OF THE INVENTION 
     It is therefore a primary object of the present invention to provide a board-shaped heat dissipating device that provides high heat dissipation efficiency. 
     Another object of the present invention is to provide a method of manufacturing a board-shaped heat dissipating device that avoids the problem of thermal resistance. 
     A further object of the present invention is to provide a board-shaped heat dissipating device that occupies reduced space. 
     To achieve the above and other objects, the board-shaped heat dissipating device according to the present invention includes a board body, at least one heat conducting element, at least one groove, and at least one heat pipe. The board body has at least one plane face with at least one recess formed thereon. The heat conducting element has a first side correspondingly associated with the recess and an opposite second side flushing with the plane face of the board body. The at least one groove can be formed on any one of the board body and the heat conducting element, and has a closed side and an open side. The at least one heat pipe is embedded in the at least one groove and has an embedded face correspondingly associated with the closed side of the groove and a contact face flushing with the open side of the groove. 
     And, the method of manufacturing the board-shaped heat dissipating device of the present invention includes the following steps: forming at least one recess on a plane face of a board body; selectively forming at least one groove on a bottom face of the recess or a first side of a heat conducting element; applying a heat-conducting bonding medium in the formed groove; correspondingly placing at least one heat pipe in the at least one groove, pressing the at least one heat pipe against the board body or the heat conducting element and welding the at least one heat pipe to the at least one groove; fitting the first side of the heat conducting element in the recess and welding the heat conducting element to the board body; and conducting a cut operation to remove portions on a second side of the heat conducting element that are higher than the plane face of the board body, so that the second side of the heat conducting element is flush with the plane face of the board body to reduce the space occupied by the heat dissipating device. With the above arrangements, the problem of thermal resistance can be avoided and upgraded overall heat dissipation efficiency can be achieved. 
     In brief, the board-shaped heat dissipating device of the present invention provides at least the following advantages: (1) occupying only reduced space; (2) having excellent heat dissipation efficiency; and (3) avoiding the problem of thermal resistance. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The structure and the technical means adopted by the present invention to achieve the above and other objects can be best understood by referring to the following detailed description of the preferred embodiments and the accompanying drawings, wherein 
         FIG. 1  is an exploded perspective view of a board-shaped heat dissipating device according to a first embodiment of the present invention; 
         FIG. 2  is an assembled perspective view of the board-shaped heat dissipating device of  FIG. 1 ; 
         FIG. 3  is a fragmentary and enlarged sectional view of the board-shaped heat dissipating device of  FIG. 1 ; 
         FIG. 4  is an exploded perspective view of a board-shaped heat dissipating device according to a second embodiment of the present invention; 
         FIG. 5  is an assembled perspective view of the board-shaped heat dissipating device of  FIG. 4 ; 
         FIG. 6  is a fragmentary and enlarged sectional view of the board-shaped heat dissipating device of  FIG. 5 ; 
         FIG. 7  is a flowchart showing the steps included in a first method for manufacturing the board-shaped heat dissipating device of  FIG. 1 ; 
         FIGS. 8 to 13  are sectional views illustrating the manufacture of the board-shaped heat dissipating device of  FIG. 1  according to the first method of the present invention; 
         FIG. 14  is a flowchart showing the steps included in a second method for manufacturing the board-shaped heat dissipating device of  FIG. 4 ; and 
         FIGS. 15 to 19  are sectional views illustrating the manufacture of the board-shaped heat dissipating device of  FIG. 4  according to the second method of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Please refer to  FIGS. 1 and 2  that are exploded and assembled perspective views, respectively, of a board-shaped heat dissipating device  1  according to a first embodiment of the present invention, and to  FIG. 3  that is a fragmentary and enlarged sectional view of  FIG. 2 . As shown, the board-shaped heat dissipating device  1  in the first embodiment includes a board body  11 , at least one heat conducting element  12 , at least one groove  111 , and at least one heat pipe  13 . In the illustrated first embodiment, there are provided one heat conducting element  12 , two grooves  111  and two heat pipes  13 . The board body  11  has at least one plane face  112 , on which at least one recess  113  is formed. The heat conducting element  12  has a first side  121  being correspondingly associated with the recess  113 , and a second side  122  opposite to the first side  121  and flushing with the plane face  112  of the board body  11 . The grooves  111  are formed on the board body  11 , and each of the grooves  111  has a closed side  1111  and an open side  1112 . The heat pipes  13  are received in the grooves  111  in one-to-one correspondence, and each of the heat pipes  13  includes an embedded face  131  correspondingly associated with the closed side  1111  of the groove  111  and a contact face  132  corresponding to and flushing with the open side  1112  of the groove  111 . A heat-conducting bonding medium  15 , which can be any one of solder paste and solder stick, is applied on the closed side  1111  of each of the grooves  111 . The contact face  132  of each of the heat pipes  13  is located opposite to the embedded face  131 , and has two lateral edges joining two lateral edges of the embedded face  131 . The contact face  132  is a flat face, and the embedded face  131  has a cross sectional shape the same as that of the closed side  1111  of the groove  111 . Further, the heat conducting element  12  is made of a material selected from the group consisting of copper and aluminum. 
       FIGS. 4 and 5  are exploded and assembled perspective views, respectively, of a board-shaped heat dissipating device  1  according to a second embodiment of the present invention, and  FIG. 6  is a fragmentary and enlarged sectional view of  FIG. 5 . As shown, the board-shaped heat dissipating device  1  in the second embodiment includes a board body  11 , at least on heat conducting element  12 , at least one groove  111 , and at least one heat pipe  13 . In the illustrated second embodiment, there are provided one heat conducting element  12 , two grooves  111  and two heat pipes  13 . The board body  11  has at least one plane face  112 , on which at least one recess  113  is formed. The heat conducting element  12  has a first side  121  correspondingly associated with the recess  113 , and a second side  122  opposite to the first side  121  and flushing with the plane face  112  of the board body  11 . The grooves  111  are formed on the first side  121  of the heat conducting element  12 , and each of the grooves  111  has a closed side  1111  and an open side  1112 . The heat pipes  13  are received in the grooves  111  in one-to-one correspondence, and each of the heat pipes  13  includes an embedded face  131  correspondingly associated with the closed side  1111  of the groove  111  and a contact face  132  corresponding to and flushing with the open side  1112  of the groove  111 . A heat-conducting bonding medium  15 , which can be any one of solder paste and solder stick, is applied on the closed side  1111  of each of the grooves  111 . The contact face  132  of each of the heat pipes  13  is located opposite to the embedded face  131 , and has two lateral edges joining two lateral edges of the embedded face  131 . The contact face  132  is a flat face, and the embedded face  131  has a cross sectional shape the same as that of the closed side  1111  of the groove  111 . Further, the heat conducting element  12  is made of a material selected from the group consisting of copper and aluminum. 
       FIG. 4  is a flowchart showing the steps included a first method for manufacturing the board-shaped heat dissipating device  1  according to the first embodiment of the present invention; and  FIGS. 8 to 13  are sectional views illustrating the manufacture of the board-shaped heat dissipating device  1  using the first method of  FIG. 4 . The first method includes the following steps: 
     Step  21 : Forming at least one recess on a plane face of a board body. In the step  21 , as shown in  FIG. 8 , the board body  11  has a plane face  112 , on which at least one recess  113  is formed through milling or other cut operations. In the illustrated first manufacturing method, the recess  113  is formed by milling. However, it is understood the recess  113  can be formed in other manners without being limited to milling. Further, the recess  113  can have a square, a round, or any other geometrical shape. In the illustrated first manufacturing method, the recess  113  is square in shape. However, it is understood the recess  113  is not limited to the square shape. Basically, the recess  113  has a shape corresponding to that of a heat conducting element  12  to be received therein. 
     Step  22 : Forming at least one groove on a bottom face of the recess, and applying a heat-conducting bonding medium in the formed groove. In the step  22 , at least one groove  111  is formed on a bottom face of the recess  113  through milling or other machining manners, and a heat-conducting bonding medium  15  is applied in the groove  111 , as shown in  FIG. 9 . The heat-conducting bonding medium  15  can be any one of solder paste and solder stick. 
     Step  23 : Correspondingly placing at least one heat pipe in the at least one groove, forcing the at least one heat pipe against the board body, and welding the at least one heat pipe to the at least one groove. In the step  23 , as shown in  FIG. 10 , at least one heat pipe  13  is correspondingly placed in the at least one groove  111 , and the heat pipe  13  in the groove  111  is properly adjusted in position in order to closely attach to the groove  111 . Then, the board body  11  with the at least one heat pipe  13  is positioned between an upper mold  51  and a lower mold  52  of a press machine  5 , as shown in  FIG. 11 . When the upper mold  51  is pressed against the board body  11  and the at least one heat pipe  13  placed in the groove  111 , the heat pipe  13  is firmly forced into the groove  111 , such that a bottom side of the heat pipe  13  is tightly attached to and associated with the groove  111 , and a top side of the heat pipe  13  is flattened to provide a contact face. 
     Step  24 : Fitting a first side of a heat conducting element in the recess to bear on the contact face of the at least one heat pipe, and welding the heat conducting element to the heat pipe and the board body. In the step  24 , as shown in  FIG. 12 , a heat conducting element  12  is fitted in the recess  113  with a first side  121  of the heat conducting element  12  correspondingly contacting with the bottom face of the recess  113  and tightly bearing against the contact face of the at least one heat pipe  13 . And then, the board body  11 , the heat pipe  13  and the heat conducting element  12  are welded to one another to remove any clearance among them. 
     Step  25 : Conducting a cut operation to remove portions on a second side of the heat conducting element that are higher than the plane face of the board body, so that the second side of the heat conducting element is flush with the plane face of the board body. In the step  25 , as shown in  FIG. 13 , portions on a second side  122  of the heat conducting element  12  that are higher than the plane face  112  of the board body  11  are removed through a cut operation, so that the second side  122  of the heat conducting element  12  is flush with the plane face  112  to reduce the space being occupied by the heat dissipating device  1  and avoid the problem of thermal resistance. The cut operation can be any one of milling, grinding, and planning. In the illustrated first method, a sand wheel  4  is used to grind off the portions on the second side  122  of the heat conducting element  12  that are higher than the plane face  112  of the board body  11 . 
       FIG. 14  is a flowchart showing the steps included a second method for manufacturing the board-shaped heat dissipating device  1  according to the second embodiment of the present invention; and  FIGS. 15 to 19  are sectional views illustrating the manufacture of the board-shaped heat dissipating device  1  using the second method of  FIG. 14 . The second method includes the following steps: 
     Step  31 : Forming at least one recess on a plane face of a board body. In the step  31 , as shown in  FIG. 15 , the board body  11  has a plane face  112 , on which at least one recess  113  is formed through milling or other cut operations. In the illustrated second manufacturing method, the recess  113  is formed by milling. However, it is understood the recess  113  can be formed in other manners without being limited to milling. Further, the recess  113  can have a square, a round, or any other geometrical shape. In the illustrated first manufacturing method, the recess  113  is square in shape. However, it is understood the recess  113  is not limited to the square shape. Basically, the recess  113  has a shape corresponding to that of a heat conducting element  12  to be received therein. 
     Step  32 : Forming at least one groove on a first side of a heat conducting element, and applying a heat-conducting bonding medium in the formed groove. In the step  32 , at least one groove  111  is formed on a first side  121  of a heat conducting element  12  through milling or other cutting manners, and a heat-conducting bonding medium  15  is applied in the groove  111 , as shown in  FIG. 16 . The heat-conducting bonding medium  15  can be any one of solder paste and other heat-conducting media that have good heat conducting performance and bonding ability. 
     Step  33 : Correspondingly placing at least one heat pipe in the at least one groove, forcing the at least one heat pipe against the heat conducting element, and welding the at least one heat pipe to the at least one groove. In the step  33 , as shown in  FIG. 17 , at least one heat pipe  13  is correspondingly placed in the at least one groove  111 , and the heat pipe  13  in the groove  111  is properly adjusted in position in order to closely attach to the face of a closed side  1111  of the groove  111 . Then, the heat conducting element  12  with the at least one heat pipe  13  is positioned between an upper mold  51  and a lower mold  52  of a press machine  5 , as shown in  FIG. 17 . When the upper mold  51  is pressed against the heat conducting element  12  and the at least one heat pipe  13  placed in the groove  111 , the heat pipe  13  is firmly forced into the groove  111  to associate with the groove  111 , and a bottom side of the heat pipe  13  is flattened to provide a contact face  132 . Meanwhile, the heat pipe  13  is welded to the groove  111  to ensure firm and stable association of the two with each other, and to remove any clearance between the heat pipe  13  and the groove  111  to avoid thermal resistance. 
     Step  34 : Fitting the first side of the heat conducting element in the recess formed on the plane face of the board body to bear the contact face of the at least one heat pipe on a bottom face of the recess, and welding the heat conducting element to the heat pipe and the board body. In the step  34 , as shown in  FIG. 18 , the heat conducting element  12  is fitted in the recess  113  with the contact face  132  of the heat pipe  13  firmly bearing on a bottom face of the recess  113 . And then, the at least one groove  111 , the at least one heat pipe  13  and the heat conducting element  12  are welded to one another to ensure firm and tight connection of them to one another and to remove any clearance among them to avoid thermal resistance. 
     Step  35 : Conducting a cut operation to remove portions on a second side of the heat conducting element that are higher than the plane face of the board body, so that the second side of the heat conducting element is flush with the plane face of the board body. In the step  35 , as shown in  FIG. 19 , portions on a second side  122  of the heat conducting element  12  that are higher than the plane face  112  of the board body  11  are removed through a cut operation, so that the second side  122  of the heat conducting element  12  is flush with the plane face  112  to reduce the space being occupied by the heat dissipating device  1  and avoid the problem of thermal resistance. The cut operation can be any one of milling, grinding, and planning. In the illustrated first method, a sand wheel  4  is used to grind off the portions on the second side  122  of the heat conducting element  12  that are higher than the plane face  112  of the board body  11 . 
     The present invention has been described with some preferred embodiments thereof and it is understood that many changes and modifications in the described embodiments can be carried out without departing from the scope and the spirit of the invention that is intended to be limited only by the appended claims.