Abstract:
A refrigerant tank includes a base plate made of cooper and a reinforcing frame made of stainless steel. A block made of copper extends through the reinforcing frame and has one face in contact with the base plate and an opposite face in contact with a heating body. Heat generated by the heating body is transferred through the cooper block and through the copper base plate to refrigerant inside the refrigerant tank. The stainless steel reinforcing frame provides strength to the refrigerant tank to allow the heating body to be pressed against the heating tank.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a boiling and cooling device for cooling a heating body of a semiconductor element by the transfer of latent heat generated when a refrigerant is boiled and condensed. 
   2. Description of the Related Art 
   According to the boiling and cooling device disclosed in the official gazette of JP-A-2004-37074, a material and a method of manufacturing a container to compose a refrigerant tank are not described. However, when consideration is given to the heat conduction characteristics, it is assumed that the boiling and cooling device is formed out of copper by means of press forming, forging or cutting. A refrigerant tank and a radiating section are usually joined to each other by means of brazing. 
   On the other hand, in the case where a heat sink is applied to a heating body, in order to reduce the contact heat resistance, it is usually required that the heat sink is attached by being strongly pushed to the heating body. Therefore, mechanical strength (rigidity) is required, of the container of the refrigerant tank of a boiling and cooling device, so that the container cannot be deformed even when a pushing force is applied to the container and so that the heat sink can be pushed to the heat generating body by an appropriate force. 
   However, the following problems may be encountered. In general, when a copper material is heated at the time of brazing, it is softened and the rigidity is lowered. Accordingly, the container of the cooling tank is easily deformed when a force is applied to it, and it is impossible to push the heat sink to the heating body with an appropriate force. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a boiling and heating device, in which a refrigerant tank and a heating section are joined by being brazed to each other, characterized in that: while making the most of the good heat transfer characteristic of copper, a heat sink can be pushed to the heating body with an appropriate force. 
   In order to accomplish the above object, according to a first aspect of the present invention, there is provided a boiling and cooling device comprising: a refrigerant tank ( 1 ) for storing a liquid-phase refrigerant, on the outer surface of which a heating body ( 90 ) is attached; and a radiating section ( 2 ) for cooling and condensing the refrigerant, which is boiled by heat of the heating body ( 90 ), and for returning the condensed refrigerant to the refrigerant tank ( 1 ), wherein the refrigerant tank ( 1 ) and the radiating section ( 2 ) are joined to each other by means of brazing, a container composing the refrigerant tank ( 1 ) including: a block ( 13 ) made of copper, one face of which is exposed inside the refrigerant tank ( 1 ), the other face of which is contacted with the heating body ( 90 ); and a lamination plate ( 12 ) composed of three layer structural material in which a reinforcing material ( 122 ) is interposed between skins ( 121 ) made of copper, the lamination plate ( 12 ) being joined to the block ( 13 ), wherein the reinforcing material ( 122 ) is made of material, the rigidity of which, after the completion of the brazing process, is higher than the rigidity of copper. 
   Due to the foregoing, the rigidity of the container composing the refrigerant tank can be ensured by a reinforcing member after the completion of the brazing process. Therefore, when the refrigerant container is pushed to the heating body, deformation of the refrigerant tank container can be suppressed. Further, heat can be transferred between the refrigerant and the heating body via a block made of copper, the heat transfer characteristic of which is good. Therefore, while making the most of the good heat transfer characteristic of copper, the refrigerant tank container can be pushed to the heat generating body by an appropriate force. 
   In this connection, as in a third aspect of the present invention, steel can be employed as the reinforcing material ( 122 ). 
   In this connection, the terminology “copper” used in this specification includes any of a pure copper and a copper alloy. 
   According to a boiling and cooling device of a second aspect of the present invention, the lamination plate ( 12 ) includes an opening portion ( 123 ) for communicating the inside with the outside of the refrigerant tank ( 1 ), and the block ( 13 ) is arranged in the opening portion ( 123 ). 
   Due to the foregoing, it is possible to easily realize such a structure that one face of the block is exposed to the inside of the refrigerant tank and the other face is contacted with the heat generating body. 
   According to a fourth aspect of the present invention, a boiling and cooling device comprises: a refrigerant tank ( 1 ) for storing a liquid-phase refrigerant, on the outer surface of which a heating body ( 90 ) is attached; and a radiating section ( 2 ) for cooling and condensing the refrigerant, which is boiled by heat of the heating body ( 90 ), and for returning the condensed refrigerant to the refrigerant tank ( 1 ), wherein the refrigerant tank ( 1 ) and the radiating section ( 2 ) are joined to each other by means of brazing, a container composing the refrigerant tank ( 1 ) including: a base plate made of copper, one face of which is exposed inside the refrigerant tank ( 1 ); a block ( 18 ) made of copper, one face of which is contacted with the base plate ( 16 ), the other face of which is contacted with the heating body ( 90 ); and a frame ( 17 ) for reinforcement arranged in a portion of the base plate ( 16 ) with which the block ( 18 ) is not contacted, wherein the frame ( 17 ) is made of material, the rigidity of which, after the completion of the brazing process, is higher than the rigidity of copper. 
   Due to the foregoing, the rigidity of the container composing the refrigerant tank can be maintained by the frame after the completion of brazing. Therefore, when the refrigerant container is pushed to the heating body, deformation of the refrigerant tank container can be suppressed. Further, heat can be transferred between the refrigerant and the heating body via the base plate and the block made of copper, the heat transfer characteristic of which is good. Therefore, while making the most of the high heat transfer characteristic of copper, the refrigerant tank container can be pushed to the heat generating body by an appropriate force. 
   In this connection, as in an eighth aspect of the present invention, steel can be employed as the frame ( 17 ). 
   According to a boiling and cooling device of a fifth aspect of the present invention, the frame ( 17 ) is located on the outer surface side of the base plate ( 16 ) and provided with an opening portion ( 171 ) for communicating the outer surface of the base plate ( 16 ) with the outside of the refrigerant tank ( 1 ), and the block ( 18 ) is arranged in the opening portion ( 171 ). 
   In this connection, in the case where the lamination plate has an opening portion for communicating the inside of the refrigerant tank with the outside like the second aspect of the present invention, the refrigerant may leak out from the joining portion in which the lamination plate is joined to the block. However, the opening portion of the frame in the fifth aspect of the present invention does not communicate the inside of the refrigerant tank with the outside. Accordingly, there is no possibility that the refrigerant will leak out from the opening portion. 
   According to a sixth aspect of the present invention, a boiling and cooling device comprises: a refrigerant tank ( 1 ) for storing a liquid-phase refrigerant, on the outer surface of which a heating body ( 90 ) is attached; and a radiating section ( 2 ) for cooling and condensing the refrigerant, which is boiled by heat of the heating body ( 90 ), and for returning the condensed refrigerant to the refrigerant tank ( 1 ), wherein the refrigerant tank ( 1 ) and the radiating section ( 2 ) are joined to each other by means of brazing, a container composing the refrigerant tank ( 1 ) including: a base plate ( 16 ) made of copper, one face of which is exposed inside the refrigerant tank ( 1 ), the other face of which is contacted with the heating body ( 90 ); and a frame ( 17 ) for reinforcement arranged in a portion of the base plate ( 16 ) with which the heating body ( 90 ) is not contacted, wherein the frame ( 17 ) is made of material, the rigidity of which, after the completion of the brazing process, is higher than the rigidity of copper. 
   Due to the foregoing, the rigidity of the container composing the refrigerant tank can be maintained by the frame after the completion of brazing. Therefore, when the refrigerant container is pushed to the heating body, deformation of the refrigerant tank container can be suppressed. Further, heat can be transferred between the refrigerant and the heating body via the base plate made of copper, the heat transfer characteristic of which is good. Therefore, while making the most of the good heat transfer characteristic of copper, the refrigerant tank container can be pushed to the heat generating body by an appropriate force. 
   In this connection, as in an eighth aspect of the present invention, steel can be employed as the frame ( 17 ). 
   According to a boiling and cooling device of a seventh aspect of the present invention, the frame ( 17 ) is located on the outer surface side of the base plate ( 16 ) and provided with an opening portion ( 171 ) for communicating the outer surface of the base plate ( 16 ) with the outside of the refrigerant tank ( 1 ), and a portion of the base plate ( 16 ) with which the heating body ( 90 ) is contacted is protruded from the opening portion ( 171 ) to the outside of the refrigerant tank ( 1 ). 
   In this connection, in the case where the lamination plate has an opening portion for communicating the inside of the refrigerant tank with the outside as in the second aspect of the present invention, the refrigerant may leak out from the joining portion in which the lamination plate is joined to the block. However, the opening portion of the frame in the seventh aspect of the present invention does not communicate the inside of the refrigerant tank with the outside. Accordingly, there is no possibility that the refrigerant will leak out from the opening portion. 
   As nothing corresponding to the block provided in the fourth aspect of the present invention is needed, the structure can be made simple and the low manufacturing cost can be realized. Further, there is no heat resistance at the contact face of the block with the base plate. Therefore, the heat transfer characteristic can be enhanced. 
   A portion on the base plate, with which the heat generating body is contacted, is protruded. Therefore, the base plate and the heat generating body can easily contact with each other. 
   Incidentally, the reference numerals in parentheses, to denote the above means, are intended to show the relationship of the specific means which will be described later in an embodiment of the invention. 
   The present invention may be more fully understood from the description of preferred embodiments of the invention set forth below, together with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is a front view showing a boiling and cooling device of the first embodiment of the present invention; 
       FIG. 2  is a right side view of  FIG. 1 ; 
       FIG. 3  is a plan view of  FIG. 1 ; 
       FIG. 4  is a side view showing a state in which a heating body is attached to the boiling and cooling device of the first embodiment of the present invention; 
       FIG. 5  is a sectional view taken on line A A in  FIG. 1 ; 
       FIG. 6  is an exploded perspective view showing a primary portion of the boiling and cooling device shown in  FIG. 1 ; 
       FIG. 7  is a sectional view showing a primary portion of the boiling and cooling device of the second embodiment of the present invention; 
       FIG. 8  is an exploded perspective view showing a primary portion of the boiling and cooling device of the second embodiment of the present invention; 
       FIG. 9  is a sectional view showing a primary portion of the boiling and cooling device of the third embodiment of the present invention; and 
       FIG. 10  is an exploded perspective view showing a primary portion of the boiling and cooling device of the third embodiment of the present invention. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First of all, the first embodiment of the present invention will be explained below.  FIG. 1  is a front view showing a boiling and cooling device of the first embodiment of the present invention,  FIG. 2  is a right side view of  FIG. 1 ,  FIG. 3  is a plan view of  FIG. 1 ,  FIG. 4  is a side view showing a state in which a heating body is attached to the boiling and cooling device of the first embodiment of the present invention,  FIG. 5  is a sectional view taken on line A-A in  FIG. 1 , and  FIG. 6  is an exploded perspective view showing a primary portion of the boiling and cooling device shown in  FIG. 1 . 
   The boiling and cooling device shown in  FIGS. 1 to 4  is used for cooling the heat generating body  90  of a semiconductor element. The boiling and cooling device includes: a refrigerant tank  1  for storing a liquid phase refrigerant inside, on to the outer surface of which the heating body  90  is attached; and a radiating section  2  which cools and condenses the refrigerant boiling with the heat generated by the heating body  90  and then returns the condensed refrigerant to the refrigerant tank  1 . 
   The refrigerant tank  1  is a flat-box-shaped container, which is formed when the cover plate  11  made of copper and the lamination plate  12  are joined to each other so that a space for storing liquid phase refrigerant can be formed inside. 
   As shown in  FIGS. 5 and 6 , the lamination plate  12  is composed of a three layer structural member in which the reinforcing member  12  is interposed between pieces of the skin  121  made of copper. The lamination plate  12  includes a circular opening portion  123 , which communicates the inside of the refrigerant tank  1  with the outside, into which the block  13  described later is inserted. The lamination plate  12  also includes four flange portions  125  having a hole  124  into which the bolt  92  described later is inserted. 
   The reinforcing member  122  is made of material, the rigidity of which, after the completion of the brazing process, is higher than that of copper. In this embodiment, the reinforcing member  122  is made of stainless steel. In this connection, even after diffusion joining of copper is conducted on stainless steel at about 1100° C. and even after brazing is conducted at 600 to 800° C., stainless steel is not softened and can maintain a high mechanical strength (rigidity). 
   The block  13  includes: a first columnar portion  131  made of copper and formed into a columnar shape; and a second columnar portion  132 , the diameter of which is larger than that of the first columnar portion  131 . Concerning the block  13 , the first columnar portion  131  is press-fitted into the opening portion  123  of the lamination plate  12  until the second columnar portion  132  comes into contact with the skin  121  of the lamination plate  12  while the second columnar portion  132  is positioned inside the refrigerant tank  1 . Due to the foregoing, an end face of the first columnar portion  131  is exposed outside the refrigerant tank  1 , so that the refrigerant body  90  can be contacted with an end face of the first columnar portion  131 . 
   At the time of brazing the entire boiling and cooling device so as to integrate it into one body, the press-fitting portion, in which the first columnar portion  131  is press-fitted into the opening portion  123 , is tightly sealed with the ring-shaped brazing material  14  made of a phosphor copper or a silver brazing metal arranged outside the engaging portion in which the block  13  and the lamination plate  12  are engaged with each other. 
   The wick  15  is provided in the refrigerant tank  1 . Before the entire boiling and cooling device is integrally brazed, the wick  15  is previously joined to the block  13  by diffusion. As well known, the wick  15  is porous. In this embodiment, the wick  15  is made of foamed copper. 
   As shown in  FIGS. 1 to 4 , the radiating portion  2  includes: a flat-box-shaped header  21  which is formed by joining two plates so that a space can be formed inside; a plurality of tubes  22  which communicate the header  21  with the refrigerant tank  1  so as to circulate the refrigerant between the header  21  and the refrigerant tank  1 ; fins  23  interposed between the tubes  22  so as to extend the radiation area; and a side plate  24  for connecting the header  21  with the refrigerant tank  1 . In this connection, all the header  21 , the tubes  22 , the fins  23  and the side plate  24  are made of copper. 
   In the boiling and cooling device described above, after the wick  15  has been previously joined to the block  13  by diffusion, the components are integrally brazed to each other by the brazing metal provided between the components to be joined. 
   A predetermined amount of refrigerant is charged into the inner space of the boiling and cooling device which had been evacuated. Therefore, the inner space of the boiling and cooling device is maintained in a saturation state. In this case, water is used for the refrigerant. In this connection, not only water but also alcohol, fluorocarbon and chlorofluorocarbons may be used for the refrigerant. 
   The heating body  90  is mounted on the printed board  91 . When the printed board  91  and the boiling and cooling device are joined to each other by the bolts  92  and the nuts  93 , the block  13  is pushed to the heating body  90 . 
   Next, operation of the boiling and cooling device composed as described above will be explained below. 
   Heat generated by the heating body  90  is transferred to the wick  15  via the block  13 , and the liquid phase refrigerant in the wick  15  is boiled and vaporized by the heat. The thus vaporized gas-phase refrigerant rises in the tubes  22  and flows to the header  21 . Heat is exchanged between the gas-phase refrigerant and the outside air when the gas-phase refrigerant flows in the tubes  22 , so that the gas-phase refrigerant can be cooled. The thus cooled and condensed refrigerant descends in the tubes  22  and returns into the refrigerant tank  1 . 
   As described above, the heat generated by the heating body  90  is transferred to the refrigerant and carried to the radiating portion  2 . When the gas-phase refrigerant is condensed in this radiating portion  2 , the heat is discharged as the latent heat of condensation. This latent heat of condensation is radiated to the outside air via the fins  23 , so that the heating body  90  can be cooled. 
   In this embodiment, the rigidity of the container, which composes the refrigerant tank  1  can be maintained by the reinforcing member  122  after the completion of the brazing process. Therefore, deformation of the refrigerant container can be suppressed at the time of pushing the refrigerant container to the heating body  90 . Further, heat can be transferred between the refrigerant and the heating body  90  via the block  13  made of copper, the heat transfer property of which is good. Therefore, while making the most of the good heat transfer property of copper, the refrigerant tank container can be pushed to the heating body  90  with an appropriate force. 
   As the skin  121  of the lamination plate  12  is made of copper, it is possible to suppress the generation of non-condensation gas by corrosion, and further it is possible to easily join the block  13  made of copper to the lamination plate  12  by means of brazing in which a common brazing metal such as a phosphor copper or a silver copper is used. 
   When the block  13  is formed into a columnar shape having a step portion and the second columnar portion  132 , the diameter of which is large, is contacted with the skin  121  of the lamination plate  12 , it is possible to prevent the brazing metal  14  from being sucked into the wick  15  in the case where brazing is conducted on the outside of the engaging portion of the block  13  and the lamination plate  12  with the ring-shaped brazing metal  14 . 
   Next, the second embodiment of the present invention will be explained below.  FIG. 7  is a sectional view showing a primary portion of the boiling and cooling device of the second embodiment of the present invention, and  FIG. 8  is an exploded perspective view showing a primary portion of the boiling and cooling device of the second embodiment of the present invention. The constitution of a container composing the refrigerant tank  1  in the present embodiment is different from that of the first embodiment. Note that when describing the second embodiment, the same reference numerals denote constituent members which are the same as or similar to those described with reference to the first embodiment, and an explanation is not given. 
   As shown in  FIGS. 7 and 8 , the refrigerant tank  1  is formed into a flat-box-shaped container, in which a space for storing the liquid-phase refrigerant is formed, when the cover plate  11  (shown in  FIG. 1 ) made of copper and the base plate  16  made of copper are joined to each other. The reinforcing frame  17  is arranged outside the base plate  16 . 
   The frame  17  includes: a circular opening portion  171  into which the block  18  described later is inserted; and four flange portions  173  having a hole  172  into which a bolt is inserted as illustrated in  FIG. 8 . The frame  17  is made of material, the rigidity of which, after the brazing process, is higher than that of copper. In this embodiment, the frame  17  is made of stainless steel. 
   The block  18  is made of copper. The block  18  includes: a first columnar portion  181  formed into a columnar shape: and a second columnar portion  182  formed into a columnar shape, the diameter of which is smaller than that of the first columnar portion  181 . The second columnar portion  182  of the block  18  is inserted into the opening portion  171  of the frame  17  and an end face of the second columnar portion  182  is contacted with the base plate  16 . 
   The frame  17  is interposed between the first columnar portion  181  of the block  18  and the base plate  16 . An end face of the first columnar portion  181  is exposed outside the refrigerant tank  1 , and the heating body  90  (shown in  FIG. 1 ) is contacted with the end face of the first columnar portion  181 . Due to this structure, heat generated by the heating body  90  is transferred to the wick  15  via the base plate  16  and the block  18 . 
   In this connection, the base plate  16 , the frame  17  and the block  18  are simultaneously brazed to each other when the entire boiling and cooling device is integrally brazed into one body. 
   In this embodiment, the rigidity of the container composing the refrigerant tank  1  after the completion of brazing is maintained by the frame  17 . Therefore, deformation of the refrigerant tank container can be suppressed at the time of pushing the refrigerant tank container to the heating body  90 . Further, heat can be transferred between the refrigerant and the heating body  90  via the base plate  16  and the block  18  which are made of copper, the heat transfer characteristic of which is good. Therefore, while making the most of the good heat transfer characteristic of copper, the refrigerant tank container can be pushed to the heating body  90  by applying an appropriate force. 
   As the base plate  16  is made of copper, it is possible to suppress the generation of non-condensation gas by corrosion, and further it is possible to easily join the block  18  made of copper to the base plate  16  by means of brazing in which a common brazing metal is used. 
   As the opening portion  171  of the frame  17  does not communicate the inside with the outside of the refrigerant tank  1 , there is no possibility that the refrigerant leaks out from the opening portion  171  and that the brazing metal for joining the base plate  16  to the block  18  is sucked into the wick  15 . 
   Next, the third embodiment of the present invention will be explained below.  FIG. 9  is a sectional view showing a primary portion of the boiling and cooling device of the third embodiment, and  FIG. 10  is an exploded perspective view showing the primary portion of the boiling and cooling device of the third embodiment. This embodiment is composed in such a manner that the shape of the base plate  16  of the second embodiment is changed so that the block  18  can be eliminated. In this connection, like reference characters are used to indicate like parts in the second and the third embodiment and the explanations are omitted here. 
   As shown in  FIGS. 9 and 10 , a portion of the base plate  16  is embossed outwardly so as to form a protruding portion  161 . This protruding portion  161  is inserted into the opening portion  171  of the frame  17  and protruded outside exceeding the opening portion  171 , and an outer surface of this protruding portion  161  is contacted with the heating body  90  (shown in  FIG. 1 ). Due to this structure, heat generated by the heating body  90  is transferred to the wick  15  via the base plate  16 . 
   In this connection, the base plate  16  and the block  18  are simultaneously brazed to each other when the entire boiling and cooling device is integrally brazed into one body. 
   In this embodiment, the rigidity of the container composing the refrigerant tank  1  after the completion of brazing is maintained by the frame  17 . Therefore, deformation of the refrigerant tank container can be suppressed at the time of pushing the refrigerant tank container to the heating body  90 . Further, heat can be transferred from the refrigerant to the heating body  90  via the base plate  16  which is made of copper, the heat transfer characteristic of which is good. Therefore, while making the most of the good heat transfer characteristic of copper, the refrigerant tank container can be pushed to the heating body  90  by applying an appropriate force. 
   As the base plate  16  is made of copper, it is possible to suppress the generation of non-condensation gas by corrosion. 
   As the opening portion  171  of the frame  17  does not communicate the inside with the outside of the refrigerant tank  1 , there is no possibility that the refrigerant will leak out from the opening portion  171 . 
   In this embodiment, it is unnecessary to provide the block  18  which is needed in the second embodiment. Therefore, the structure can be made simple and the manufacturing cost can be reduced. Further, as no heat resistance exists between the block  18  and the base plate  16 , the heat transfer characteristic can be improved. 
   Finally, another embodiment will be explained below. In the embodiments described above, the reinforcing member  122  or the frame  17  is made of stainless steel. However, the reinforcing member  122  or the frame  17  may be made of the other iron material such as carbon steel. 
   In the second and the third embodiment, the base plate  16  and the frame  17  are integrated with each other into one body by means of brazing. However, the base plate  16  and the frame  17  may be integrated with each other by means of caulking. 
   While the invention has been described by reference to specific embodiments chosen for purposes of illustration, it should be apparent that numerous modifications could be made thereto, by those skilled in the art, without departing from the basic concept and scope of the invention.