Abstract:
Disclosed is a corrugated-fin type radiator ( 1 ), which comprises corrugated fins ( 10 ), and a support substrate ( 20 ) having a plurality of fixing grooves ( 23 ) defined by side walls ( 24 ) and a bottom ( 25 ). The bottom ( 25 ) has a ridge ( 26 ) at least in its portion, and the side walls ( 24 ) are formed of a vertical wall ( 24   a ), a tapered wall ( 24   b ) and a corner ( 24   c ). A fin fixing portion ( 14 ) is fixed along the side walls ( 24 ) and the bottom ( 25 ) of the fixing grooves ( 23 ). Also disclosed is a method for manufacturing the corrugated-fin type radiator ( 1 ), which comprises a substrate manufacturing step, a fin shaping step and a fixing step. Thus, it is possible to provide the corrugated-fin type radiator capable of improving a radiation efficiency, and a method for manufacturing the radiator.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a radiator for cooling, for example, a semiconductor element such as a transistor, an LSI, and a microprocessor, that generates heat during operation, and in particular to a corrugated-fin type radiator including corrugated fins. 
         [0003]    2. Description of the Related Art 
         [0004]    There are various types of radiators in general for cooling a semiconductor element. A corrugated-fin type radiator is known, in which corrugated fins are disposed on the support substrate on which a semiconductor element is mounted, thereby expanding the radiation area and improving the cooling effect. 
         [0005]    A conventional corrugated-fin type radiator is, for example, disclosed in JP3602806. Hereinafter such a conventional corrugated-fin type radiator will be explained with reference to  FIGS. 4A to 4B .  FIG. 4A  shows a structure in which a conventional corrugated-fin type radiator having a fin fixing portion of the corrugated-fin is fixed on a fixing groove.  FIG. 4B  is a partially enlarged sectional view of the fixing groove and its vicinity on which the fin fixing portion is fixed. As shown in  FIG. 4A , a conventional corrugated-fin type radiator  100  is mainly formed of a corrugated fin  110  and a support substrate  120  with a plurality of fin-fixing grooves  123 . The fin-fixing groove  123  includes a flat bottom  125 , tapered walls  124  spreading from an opening side, and corners  127  with a curved surface between the tapered wall  124  and the bottom  125 . A corrugated fin fixing portion  114  of the corrugated fin  110  includes a projecting portion  111  which is a lower end part of  114  projecting toward the fin-fixing groove  123 , and is so formed as to have the width smaller than the minimum width of the opening side of the fin-fixing groove  123 . 
         [0006]    By pressing the corrugated fin fixing portion  114  toward the fin-fixing groove  123  with a press fitting blade  132  which has a flat lower end, the projecting portion  111  is deformed and is pressure-bonded along the shape of the fin-fixing groove  123 , thereby the corrugated fin fixing portion  114  being fixed in the fin-fixing groove  123 . 
       DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
       [0007]    However, the corrugated-fin type radiator  100  described above still have a room for improvement. In the technical field of radiators, it is required to improve radiation efficiencies. For this purpose, an important issue is to increase the contact area and adhesion force between corrugated fins and a support substrate. 
         [0008]    In light of this background, a conventional corrugated-fin type radiator  100 , as shown in  FIG. 4B , gaps S may be formed because the corrugated fin fixing portion  114  cannot be expanded to corners  127  of the fin-fixing groove  123  with poor contact along with the corners  127 . 
         [0009]    In addition, in the conventional corrugated-fin type radiator  100 , when the projecting portion  111  of the corrugated fin fixing portion  114  is pressed with the press fitting blade  132  of which lower end is flat, the projecting portion  111  is deformed and spreads in a width direction of the fin-fixing groove  123 , and when it reaches the corner  127 , then it is pressed up in a height direction and deformed. Due to this deformation, a central part of the corrugated fin fixing portion  114  might rise and gaps S might be formed between the projecting portion  111  and the bottom  125  of the fin-fixing groove  123 . 
         [0010]    Accordingly, it is desirable to provide a corrugated-fin type radiator that can increase the contact area and adhesion force between the corrugated fins and the support substrate, and thereby improving the radiation efficiency. 
       Means for Solving the Problems 
       [0011]    The present invention is a corrugated-fin type radiator including: corrugated fins that radiate heat; and a support substrate having a plurality of fixing grooves including side walls and a bottom for fixing a part of the corrugated fins; wherein the bottom has a ridge on at least a part thereof, which is higher than the bottom and is formed in parallel to the bottom, and the side walls have vertical walls extending downward from the support substrate in a vertical direction, tapered walls extending from the vertical walls toward the bottom with increase in a distance between the tapered walls, and corners having a curved surface formed contiguously from the tapered walls to the bottom, and wherein a part of the corrugated fin is fixed along the shape of the side wall and the bottom of the fixing groove. 
         [0012]    According to the present invention, as the corrugated-fin type radiator has a ridge at least in one part of the bottom, a part of the corrugated fin is pressed by the ridge and is expanded first along the shape of the ridge. Then it is expanded along the shape of the bottom, and expanded to the side walls of the fixing groove. Thus owing to the ridge, the contact area between the corrugated fin and the support substrate can be increased. In addition, due to the ridge, the deformation quantity of the corrugated fin can be increased, thereby the pressing force applied on the corrugated fin toward the corner and the side wall located on both sides of the fixing groove are also increased. As a result, a part of the corrugated fin can be fixed on the fixing groove appropriately. Further, since the side wall of the fixing groove has a vertical wall and a tapered wall, apart of the corrugated fin can be fit and fixed into the fixing groove and a part of the corrugated fin is appropriately attached to the side wall according to the lateral-directional force between the adjacent corrugated fins. In this way, fixing a part of the corrugated fin according to the shape of the side wall and bottom of the fixing groove, the contact area between the corrugated fin and the support substrate is increased. Further, since the side wall has a corner with a curved surface, a part of the corrugated fin, which is expanded toward the corner, presses the corner, and the fixing strength of the corrugated fin to the support substrate is improved. 
         [0013]    Preferably, but not necessarily, the length of the vertical wall is made greater than or equal to one sixth and smaller than or equal to a half of the length of the side wall, the height of the ridge is made greater than or equal to one tenth and smaller than or equal to two thirds of the height of the fixing groove, the width of the lower end part of the ridge is made greater than or equal to one tenth and smaller than or equal to five sixths of the width of the fixing groove, the width of the upper part of the ridge is made greater than or equal to one eighth and smaller than or equal to four fifths of the width of the lower end part of the ridge, and the width of the upper end part is made smaller than or equal to the width of the lower end part. 
         [0014]    In this structure, a part of the corrugated fin can be appropriately fixed in a shape in accordance with the side wall, the bottom and corner, without applying an excessive force. 
         [0015]    The radius of the corner is preferably, but not necessarily, made to be greater than or equal to one sixteenth and smaller than or equal to one third of the width of the fixing groove. 
         [0016]    In this structure, a part of the corrugated fin can be fixed on the corner more appropriately. 
         [0017]    A manufacturing method according to an aspect of the present invention is a method for manufacturing a corrugated-fin type radiator described in claim  1 , including a substrate manufacturing step, a fin shaping step and a fixing step. 
         [0018]    The method of producing a corrugated-fin type radiator according to the present invention includes: a substrate manufacturing step of extruding or cutting the support substrate, forming the plurality of fixing grooves which is formed of, the side wall having the tapered wall and the corner, and of the bottom, and forming the ridge on the bottom; a fin shaping step of producing a corrugated fin by folding a metal plate to form a plurality of fin bottoms which form a lower end of the corrugated fin and are substantially parallel to the support substrate, a plurality of fin top portions which form an upper end of the corrugated fin and are substantially parallel to the support substrate, and a plurality of jointing portions which joint the fin bottom and the fin top portion and which are substantially perpendicular to the support substrate, so that the fin bottoms and the fin top portions are arranged one after the other, and so that the distance between external walls of the neighboring jointing portions is approximately equal or somewhat smaller than the opening width of the fixing groove; and a fixing step of fixing the corrugated fin on the support substrate by, inserting the fin fixing portion, which is formed of the fin bottom and a lower end of the jointing portion, into the fixing groove from the opening, fitting the fin fixing portion onto the ridge, and pressing the fin bottom toward the ridge from the gap of the jointing portion using the top of a press tool having a concave portion on top thereof, and deforming the fin fixing portion along the shape of the fixing groove, thereby the corrugated fin being fixed on the support substrate. 
       Effect of the Invention 
       [0019]    According to the present invention, the following effects can be obtained. The corrugated-fin type radiator according to the invention is capable of increasing the contact area between the corrugated fin and the support substrate, and improving the heat conduction efficiency between the support substrate and the corrugated fin. Herewith the radiation efficiency of the corrugated-fin type radiator is improved, and the fixing strength of the corrugated fin to the support substrate is also improved. 
         [0020]    In addition, according to the method for manufacturing a corrugated-fin type radiator of the present invention, the fin fixing portion is deformed along the shape of the fixing groove, thereby the contact area and the adhesion force between the corrugated fin and the support substrate are increased, and therefore the radiation characteristics of the corrugated-fin type radiator can be improved. Further, the fixing strength of the corrugated fin to the support substrate is also improved. In addition, fitting and fixing the corrugated fin on the support substrate can be performed without any special tools and the component count of a radiator can be reduced which leads to the cost reduction of the radiator. 
         [0021]    The various aspects, other advantages and further features of the present invention described above will become more apparent by describing in detail illustrative, non-limiting embodiments thereof with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]      FIG. 1A  shows an entire block diagram of a corrugated-fin type radiator in accordance with an embodiment of the present invention; 
           [0023]      FIG. 1B  shows a partially enlarged perspective view of the fixing groove shown in  FIG. 1A ; 
           [0024]      FIG. 2  shows a partially enlarged sectional view of the vicinity of the fixing groove shown in  FIG. 1 ; 
           [0025]      FIGS. 3A to 3C  show explanatory diagrams for explaining how corrugated fins are fixed to the fixing grooves; 
           [0026]      FIG. 4A  shows a conventional corrugated-fin type radiator having the fin fixing portion of the corrugated fin fixed on the fixing groove; and 
           [0027]      FIG. 4B  shows a partially enlarged sectional view of the vicinity of the fixing groove with the fin fixing portion thereof being fixed. 
       
    
    
     DESCRIPTION OF THE SYMBOLS 
       [0000]    
       
         
           
               1  corrugated-fin type radiator 
               10  corrugated fin 
               11  fin bottom 
               12  fin top portion 
               13  jointing portion 
               14  fin fixing portion 
               15  outermost fin bottom 
               20  support substrate 
               21  upper surface 
               22  lower surface 
               23  fixing groove 
               24  side wall 
               24   a  vertical wall 
               24   b  tapered wall 
               24   c  corner 
               25  bottom 
               26  ridge 
               28  engaging portion 
               28   a  engaging side wall 
               28   b  engaging bottom 
               29  clamping portion 
               31 ,  32  press tool 
               31   a  concave portion 
           
         
       
     
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0051]    Hereinafter, preferred embodiments of a corrugated-fin type radiator  1  according to the present invention will be described with reference to the drawings. 
         [0052]    As shown in  FIG. 1A , a corrugated-fin type radiator  1  includes corrugated fins  10  for radiating heat, and a support substrate  20  having a plurality of fixing grooves  23  thereon which is formed of a side wall  24  and a bottom  25  for fixing a part of the corrugated fin  10 . The corrugated fin  10  and the support substrate  20  are made of high thermal conductive materials such as copper, copper alloy, Al alloy and the like. 
         [0053]    The corrugated fin  10  includes, a fin bottom  11  which is nearly parallel to the support substrate  20  and forms the lower end of the corrugated fin, a fin top portion  12  which is nearly parallel to the support substrate  20  and forms the upper end of the corrugated fin  10 , and a jointing portion  13  which is substantially vertical to the support substrate  20  and couples the fin bottom  11  and the fin top portion  12 . The fin bottoms  11  and the fin top portions  12  are arranged one after the other. 
         [0054]    The corrugated fin  10  can be shaped by folding a long metal plate trough press forming. Meanwhile, in this embodiment, as shown in  FIG. 1A  and  FIG. 2 , the corrugated fin  10  does not have a jointing portion  13  at the outermost part thereof, and the outermost fin bottom  15  is made shorter than other fin bottoms  11  (see  FIG. 2 ). 
         [0055]    In addition, there is no restriction in the height of the jointing portion  13  of the corrugated fin  10  from the support substrate  20  as long as it is high enough for obtaining the radiation effect. Further, a width W 1  of the corrugated fin  10  may be smaller or greater than the width of support substrate  20 , and not restricted specifically. Still further, the thickness of the corrugated fin  10  may be determined as appropriate in light of the strength and so on. 
         [0056]    According to this embodiment, in the corrugated fin  10 , the fin bottom  11  and the lower end of the jointing portion  13 ,  13 , which are contiguously formed from both ends of the fin bottom  11  in the longitudinal direction, are fixed along the shape of the fixing groove  23 . Hereinafter, this portion may be referred to as “fin fixing portion” for convenience in the explanation. The fin fixing portion  14  is formed so that the width of the fin fixing portion  14  (see  FIG. 2 ), that is the width between the external walls of the jointing portion  13 , is nearly equal to or slightly smaller than the width of the opening of the fixing groove  23 , that is the width between the side walls  24 ,  24 . Herewith, the fin fixing portion  14  can be inserted smoothly into the fixing groove  23 . 
         [0057]    As shown in  FIGS. 1A and 1B , the support substrate  20  acts as a base of the corrugated-fin type radiator  1 , and has a plurality of fixing grooves  23  having a width and depth prescribed for fixing the corrugated fin  10  on the upper surface  21 . In addition, the support substrate  20  abuts to a heat source such as a semiconductor element (not shown), and conducts the heat from the heating element to the corrugated fin  10 . 
         [0058]    As shown in  FIG. 1B , the plurality of fixing grooves  23  having the side wall  24  and the bottom  25  are formed from the upper surface  21  to the lower surface  22  on the support substrate  20 . 
         [0059]    The side wall  24  is formed of, a vertical wall  24   a  which extends downward perpendicularly to the upper surface  21  of the support substrate  20 , a tapered wall  24   b  formed from the vertical wall  24   a  toward the bottom  25  increasing in diameter, and a corner  24   c  having a curved surface formed contiguously from the lower end portion of the tapered wall  24   b.    
         [0060]    It is preferable for a length L 1  of the vertical wall  24   a  to be greater than or equal to one sixth and smaller than or equal to one half of a length L 2  of the side wall  24 . If the length L 1  of the vertical wall  24   a  is smaller than or equal to one sixth of a length L 2  of the side wall  24 , it is not preferable because the length L 1  of the vertical wall  24   a  is too short and the fin fixing portion  14  may not be closely contacted properly. Meanwhile, if the length L 1  of the vertical wall  24   a  is greater than or equal to one half of a length L 2  of the side wall  24 , the angle made by the tapered wall  24   b  and the corner  24   c  becomes too steep and the fin fixing portion  14  may not be closely contacted properly, which is not preferable either. Therefore, it is more preferable to set the length L 1  of the vertical wall  24   a  to be greater than or equal to one fourth and smaller than or equal to one third of a length L 2  of the side wall  24 . 
         [0061]    It is preferable to form the corner  24   c  with a radius to be greater than or equal to one sixteenth and smaller than or equal to one third of the width of the fixing groove  23 . If the radius of the corner  24   c  is smaller than or equal to one sixteenth of the width of the fixing groove  23 , the angle of the corner  24   c  becomes too steep and the fin fixing portion  14  may not be closely contacted properly along the shape of the corner  24   c . Meanwhile, if a radius of the corner  24   c  is greater than or equal to one third of the width W 2  of the fixing groove  23 , the angle of the corner  24   c  becomes too large and the fixing strength may not be enough, which is not preferable either. Therefore, it is more preferable to form the vertical wall  24   a  with a radius to be greater than or equal to one eighth and smaller than or equal to one fourth of the width W 2  of the fixing groove  23 . 
         [0062]    The bottom  25  is formed as a flat surface nearly parallel to the upper surface  21  of the support substrate  20 , having a ridge  26  at least in one portion which is higher than the bottom  25  and is parallel to the bottom  25 . 
         [0063]    In this embodiment, the ridge  26  is formed nearly in the central region of the bottom  25 . The ridge  26  is formed so that, the height H 2  from the fixing groove  23  is greater than or equal to one tenth and smaller than or equal to two thirds of the height of the fixing groove  23 , the width W 3  of the lower end portion is greater than or equal to one tenth and smaller than or equal to five sixths of the width W 2  of the fixing groove  23 , the width W 4  of the upper end portion is greater than or equal to one eighth and smaller than or equal to four fifths of the width W 4  of the width W 3  of the lower end portion of the ridge  26 , and the width W 4  of the upper end portion of the ridge  26  is smaller than or equal to the width W 3  of the lower end portion of the ridge  26 . Herewith the contact area between the fin fixing portion  14  and the fixing groove  13  can be increased. Further, it is more preferable to set the height H 2  of the ridge  26  from the fixing groove  23  to be greater than or equal to one fourth and smaller than or equal to one half of the height of the fixing groove  23 , the width W 3  of the lower end portion of the ridge  26  to be greater than or equal to one fifth and smaller than or equal to one third of the width W 2  of the fixing groove  23 , and the width W 4  of the ridge  26  to be greater than or equal to one third and smaller than or equal to one half of the width W 3  of the ridge  26 . 
         [0064]    The support substrate  20  is produced, for example, by extruding or cutting one surface of a metal plate (the upper surface  21  in the embodiment) and forming a plurality of fixing groove  23 . 
         [0065]    In addition, an engaging portion  28  is formed on both ends of the support substrate  20  for engaging an outermost fin bottom  15 , which is located at outermost part of the corrugated fin  10 , with a jointing portion  13 , which is formed contiguously to the outermost fin bottom  15 . The engaging portion  28  includes an engaging side wall  28   a  which extends downward from the upper surface  21  in a vertical direction, and an engaging bottom  28   b  which is formed contiguously from the engaging side wall  28   a  and is parallel to the support substrate  20 . The width of the engaging portion  28  is determined to be nearly equal to the distance between the outer end of the outermost fin bottom  15  and the external wall of the jointing portion  13 . 
         [0066]    Further, a clamping portion  29  is formed outside the engaging portion  28 . The clamping portion  29  is used for clamping and fixing the outermost fin bottom  15  onto the engaging portion  28  by being crushed, and in this embodiment the clamping portion  29  is formed to be a protrusion along the outer end portion of the engaging bottom  28   b  of the engaging portion  28 . It is preferable that the height H 3  of the clamping portion  29  is made lower than the height of the engaging side wall  28   a , that is the height H 1  of the fixing groove  23 , so that, when clamping portion  29  is crushed flatly, the top thereof may not get stuck on the engaging side wall  28   a.    
         [0067]    Next, a process in which the fin fixing portion  14  is fixed onto the fixing groove  23  will be explained referring to  FIGS. 3A to 3C , and  FIGS. 1 to 2  as appropriate. As shown in  FIG. 3A , the fin fixing portion  14  of the corrugated fin  10  is inserted from the opening of the fixing groove  23  and fit and fixed onto the ridge  26 . Then, as shown in  FIG. 3B , the fin bottom  11  is pressed toward the ridge  26  of the fixing groove  23  with the tip of a press tool  31  having a concave portion  31   a . Thus, the fin bottom  11  is closely contacted along the shape of the ridge  26 , and spread widthwise in the bottom  25  of the fixing groove  23  from the ridge  26 , and finally closely contacted along the shape of the corner  24   c.    
         [0068]    Owing to the side wall  24  of the fixing groove  23 , having the vertical wall  24   a  and the tapered wall  24   b , when the fin fixing portion  14  is fit and fixed onto the fixing groove  23 , the fin fixing portion  14 , especially the jointing portion  13 ,  13  thereof is in close contact with the side wall  24  according to the lateral force between adjacent corrugated fins  20 . In addition, the side wall  24  having the corner  24   c  with a curve, can contact the fin fixing portion  14  closely onto the corner  24   c . Thus, as shown in  FIG. 3C , the fin fixing portion  14  is closely contacted and fixed along the shape of the fixing groove  23 . 
         [0069]    At the same time, by fitting the outermost jointing portion  13  and the outermost fin bottom  15  into the engaging portion  28  (see  FIG. 1B ), and by pressing the clamping portion  29  with a press tool  32  having a flat top toward an engaging bottom  28   b  (see  FIG. 1B ), the clamping portion  29  is crushed flatly according to the shape of the press tool  32  and spreads over the outermost fin bottom  15 , and presses the outermost fin bottom  15  toward the engaging bottom  28   b  (see  FIG. 1B ). Herewith, as shown in  FIG. 3C , the outermost fin bottom  15  and the jointing portion  13  are fixed onto the engaging portion  28  (see  FIG. 1B ). 
         [0070]    Thus, the corrugated fin  20  is fixed to the support substrate  10 . Meanwhile, it is preferable to make the concave portion  31   a  of the press tool  31  have a width and depth suitable for contacting the fin bottom  11  according to the shape of the ridge  26 , considering the width and height of the lower end portion of the ridge  26  and the thickness of the fin bottom  11 . 
         [0071]    According to the corrugated-fin type radiator  1  in the embodiment, by contacting the fin fixing portion  14  of the corrugated fin  10  along the shape of the fixing groove  23  of the support substrate  20 , the contact area between the corrugated fin  10  and the support substrate  20  can be increased, and the heat conduction effect from the support substrate  20  to the corrugated fin  10  can be improved. As a result, the radiation efficiency of the corrugated-fin type radiator  1  is improved. In addition, the fixing strength of the corrugated fin  10  to the support substrate  20  is improved as well. 
         [0072]    While the foregoing has described a corrugated-fin type radiator according to the embodiment, a corrugated-fin type radiator according to the present invention is not limited to the embodiment, and various modifications thereto can be made without departing from the spirit and scope of the invention